diff --git a/src/com/google/dart/compiler/backend/js/JsConstructExpressionVisitor.java b/src/com/google/dart/compiler/backend/js/JsConstructExpressionVisitor.java
index 5225780e8f4..38882310ca0 100644
--- a/src/com/google/dart/compiler/backend/js/JsConstructExpressionVisitor.java
+++ b/src/com/google/dart/compiler/backend/js/JsConstructExpressionVisitor.java
@@ -11,93 +11,92 @@ import com.google.dart.compiler.backend.js.ast.*;
  * normally be surrounded by parentheses.
  */
 public class JsConstructExpressionVisitor extends JsVisitor {
-
-  public static boolean exec(JsExpression expression) {
-    if (JsPrecedenceVisitor.exec(expression) < JsPrecedenceVisitor.PRECEDENCE_NEW) {
-      return true;
+    public static boolean exec(JsExpression expression) {
+        if (JsPrecedenceVisitor.exec(expression) < JsPrecedenceVisitor.PRECEDENCE_NEW) {
+            return true;
+        }
+        JsConstructExpressionVisitor visitor = new JsConstructExpressionVisitor();
+        visitor.accept(expression);
+        return visitor.containsInvocation;
     }
-    JsConstructExpressionVisitor visitor = new JsConstructExpressionVisitor();
-    visitor.accept(expression);
-    return visitor.containsInvocation;
-  }
 
-  private boolean containsInvocation = false;
+    private boolean containsInvocation;
 
-  private JsConstructExpressionVisitor() {
-  }
-
-  /**
-   * We only look at the array expression since the index has its own scope.
-   */
-  @Override
-  public boolean visit(JsArrayAccess x, JsContext ctx) {
-    accept(x.getArrayExpression());
-    return false;
-  }
-
-  /**
-   * Array literals have their own scoping.
-   */
-  @Override
-  public boolean visit(JsArrayLiteral x, JsContext ctx) {
-    return false;
-  }
-
-  /**
-   * Functions have their own scoping.
-   */
-  @Override
-  public boolean visit(JsFunction x, JsContext ctx) {
-    return false;
-  }
-
-  @Override
-  public boolean visit(JsInvocation x, JsContext ctx) {
-    containsInvocation = true;
-    return false;
-  }
-
-  @Override
-  public boolean visit(JsNameRef x, JsContext ctx) {
-    if (!x.isLeaf()) {
-      accept(x.getQualifier());
+    private JsConstructExpressionVisitor() {
     }
-    return false;
-  }
 
-  /**
-   * New constructs bind to the nearest set of parentheses.
-   */
-  @Override
-  public boolean visit(JsNew x, JsContext ctx) {
-    return false;
-  }
-
-  /**
-   * Object literals have their own scope.
-   */
-  @Override
-  public boolean visit(JsObjectLiteral x, JsContext ctx) {
-    return false;
-  }
-
-  /**
-   * We only look at nodes that would not normally be surrounded by parentheses.
-   */
-  @Override
-  public <T extends JsVisitable> T accept(T node) {
-    // Assign to Object to prevent 'inconvertible types' compile errors due
-    // to http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6548436
-    // reproducible in jdk1.6.0_02.
-      if (node instanceof JsExpression) {
-      JsExpression expression = (JsExpression) node;
-      int precedence = JsPrecedenceVisitor.exec(expression);
-      // Only visit expressions that won't automatically be surrounded by
-      // parentheses
-      if (precedence < JsPrecedenceVisitor.PRECEDENCE_NEW) {
-        return node;
-      }
+    /**
+     * We only look at the array expression since the index has its own scope.
+     */
+    @Override
+    public boolean visit(JsArrayAccess x, JsContext ctx) {
+        accept(x.getArrayExpression());
+        return false;
+    }
+
+    /**
+     * Array literals have their own scoping.
+     */
+    @Override
+    public boolean visit(JsArrayLiteral x, JsContext ctx) {
+        return false;
+    }
+
+    /**
+     * Functions have their own scoping.
+     */
+    @Override
+    public boolean visit(JsFunction x, JsContext ctx) {
+        return false;
+    }
+
+    @Override
+    public boolean visit(JsInvocation x, JsContext ctx) {
+        containsInvocation = true;
+        return false;
+    }
+
+    @Override
+    public boolean visit(JsNameRef x, JsContext ctx) {
+        if (!x.isLeaf()) {
+            accept(x.getQualifier());
+        }
+        return false;
+    }
+
+    /**
+     * New constructs bind to the nearest set of parentheses.
+     */
+    @Override
+    public boolean visit(JsNew x, JsContext ctx) {
+        return false;
+    }
+
+    /**
+     * Object literals have their own scope.
+     */
+    @Override
+    public boolean visit(JsObjectLiteral x, JsContext ctx) {
+        return false;
+    }
+
+    /**
+     * We only look at nodes that would not normally be surrounded by parentheses.
+     */
+    @Override
+    public <T extends JsNode> T accept(T node) {
+        // Assign to Object to prevent 'inconvertible types' compile errors due
+        // to http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6548436
+        // reproducible in jdk1.6.0_02.
+        if (node instanceof JsExpression) {
+            JsExpression expression = (JsExpression) node;
+            int precedence = JsPrecedenceVisitor.exec(expression);
+            // Only visit expressions that won't automatically be surrounded by
+            // parentheses
+            if (precedence < JsPrecedenceVisitor.PRECEDENCE_NEW) {
+                return node;
+            }
+        }
+        return super.accept(node);
     }
-    return super.accept(node);
-  }
 }
diff --git a/src/com/google/dart/compiler/backend/js/JsFirstExpressionVisitor.java b/src/com/google/dart/compiler/backend/js/JsFirstExpressionVisitor.java
index ece5af6699e..4b6a80ef4af 100644
--- a/src/com/google/dart/compiler/backend/js/JsFirstExpressionVisitor.java
+++ b/src/com/google/dart/compiler/backend/js/JsFirstExpressionVisitor.java
@@ -112,9 +112,4 @@ public class JsFirstExpressionVisitor extends JsVisitor {
     public boolean visit(JsPrefixOperation x, JsContext ctx) {
         return false;
     }
-
-    @Override
-    public boolean visit(JsRegExp x, JsContext ctx) {
-        return false;
-    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/JsPrecedenceVisitor.java b/src/com/google/dart/compiler/backend/js/JsPrecedenceVisitor.java
index bd611321d25..80698165d3c 100644
--- a/src/com/google/dart/compiler/backend/js/JsPrecedenceVisitor.java
+++ b/src/com/google/dart/compiler/backend/js/JsPrecedenceVisitor.java
@@ -10,271 +10,267 @@ import com.google.dart.compiler.backend.js.ast.JsVars.JsVar;
 /**
  * Precedence indices from "JavaScript - The Definitive Guide" 4th Edition (page
  * 57)
- *
+ * <p/>
  * Precedence 17 is for indivisible primaries that either don't have children,
  * or provide their own delimiters.
- *
+ * <p/>
  * Precedence 16 is for really important things that have their own AST classes.
- *
+ * <p/>
  * Precedence 15 is for the new construct.
- *
+ * <p/>
  * Precedence 14 is for unary operators.
- *
+ * <p/>
  * Precedences 12 through 4 are for non-assigning binary operators.
- *
+ * <p/>
  * Precedence 3 is for the tertiary conditional.
- *
+ * <p/>
  * Precedence 2 is for assignments.
- *
+ * <p/>
  * Precedence 1 is for comma operations.
  */
 class JsPrecedenceVisitor extends JsVisitor {
-  static final int PRECEDENCE_NEW = 15;
+    static final int PRECEDENCE_NEW = 15;
 
-  public static int exec(JsExpression expression) {
-    JsPrecedenceVisitor visitor = new JsPrecedenceVisitor();
-    visitor.accept(expression);
-    if (visitor.answer < 0) {
-      throw new RuntimeException("Precedence must be >= 0!");
+    public static int exec(JsExpression expression) {
+        JsPrecedenceVisitor visitor = new JsPrecedenceVisitor();
+        visitor.accept(expression);
+        if (visitor.answer < 0) {
+            throw new RuntimeException("Precedence must be >= 0!");
+        }
+        return visitor.answer;
     }
-    return visitor.answer;
-  }
 
-  private int answer = -1;
+    private int answer = -1;
 
-  private JsPrecedenceVisitor() {
-  }
-
-  @Override
-  public boolean visit(JsArrayAccess x, JsContext ctx) {
-    answer = 16;
-    return false;
-  }
-
-  @Override
-  public boolean visit(JsArrayLiteral x, JsContext ctx) {
-    answer = 17; // primary
-    return false;
-  }
-
-  @Override
-  public boolean visit(JsBinaryOperation x, JsContext ctx) {
-    answer = x.getOperator().getPrecedence();
-    return false;
-  }
-
-  @Override
-  public boolean visit(JsBlock x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsLiteral.JsBooleanLiteral x, JsContext ctx) {
-    answer = 17; // primary
-    return false;
-  }
-
-  @Override
-  public boolean visit(JsBreak x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsCase x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsCatch x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsConditional x, JsContext ctx) {
-    answer = 3;
-    return false;
-  }
-
-  @Override
-  public boolean visit(JsContinue x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsDebugger x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsDefault x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsDoWhile x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsEmpty x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsExpressionStatement x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsFor x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsForIn x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsFunction x, JsContext ctx) {
-    answer = 17; // primary
-    return false;
-  }
-
-  @Override
-  public boolean visit(JsIf x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsInvocation x, JsContext ctx) {
-    answer = 16;
-    return false;
-  }
-
-  @Override
-  public boolean visit(JsLabel x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
-
-  @Override
-  public boolean visit(JsNameRef x, JsContext ctx) {
-    if (x.isLeaf()) {
-      answer = 17; // primary
-    } else {
-      answer = 16; // property access
+    private JsPrecedenceVisitor() {
     }
-    return false;
-  }
-
-  @Override
-  public boolean visit(JsNew x, JsContext ctx) {
-    answer = PRECEDENCE_NEW;
-    return false;
-  }
-
-  @Override
-  public boolean visit(JsNullLiteral x, JsContext ctx) {
-    answer = 17; // primary
-    return false;
-  }
 
     @Override
-    public boolean visit(JsNumberLiteral.JsIntLiteral x, JsContext ctx) {
+    public boolean visit(JsArrayAccess x, JsContext ctx) {
+        answer = 16;
+        return false;
+    }
+
+    @Override
+    public boolean visit(JsArrayLiteral x, JsContext ctx) {
         answer = 17; // primary
         return false;
     }
 
     @Override
-    public boolean visit(JsNumberLiteral.JsDoubleLiteral x, JsContext ctx) {
+    public boolean visit(JsBinaryOperation x, JsContext ctx) {
+        answer = x.getOperator().getPrecedence();
+        return false;
+    }
+
+    @Override
+    public boolean visit(JsBlock x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
+
+    @Override
+    public boolean visit(JsLiteral.JsBooleanLiteral x, JsContext ctx) {
         answer = 17; // primary
         return false;
     }
 
-  @Override
-  public boolean visit(JsObjectLiteral x, JsContext ctx) {
-    answer = 17; // primary
-    return false;
-  }
+    @Override
+    public boolean visit(JsBreak x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 
-  @Override
-  public boolean visit(JsParameter x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
+    @Override
+    public boolean visit(JsCase x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 
-  @Override
-  public boolean visit(JsPostfixOperation x, JsContext ctx) {
-    answer = x.getOperator().getPrecedence();
-    return false;
-  }
+    @Override
+    public boolean visit(JsCatch x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 
-  @Override
-  public boolean visit(JsPrefixOperation x, JsContext ctx) {
-    answer = x.getOperator().getPrecedence();
-    return false;
-  }
+    @Override
+    public boolean visit(JsConditional x, JsContext ctx) {
+        answer = 3;
+        return false;
+    }
 
-  @Override
-  public boolean visit(JsProgram x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
+    @Override
+    public boolean visit(JsContinue x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 
-  @Override
-  public boolean visit(JsPropertyInitializer x, JsContext ctx) {
-    answer = 17; // primary
-    return false;
-  }
+    @Override
+    public boolean visit(JsDebugger x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 
-  @Override
-  public boolean visit(JsRegExp x, JsContext ctx) {
-    answer = 17; // primary
-    return false;
-  }
+    @Override
+    public boolean visit(JsDefault x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 
-  @Override
-  public boolean visit(JsReturn x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
+    @Override
+    public boolean visit(JsDoWhile x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 
-  @Override
-  public boolean visit(JsStringLiteral x, JsContext ctx) {
-    answer = 17; // primary
-    return false;
-  }
+    @Override
+    public void visit(JsEmpty x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 
-  @Override
-  public boolean visit(JsSwitch x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
+    @Override
+    public boolean visit(JsExpressionStatement x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 
-  @Override
-  public boolean visit(JsLiteral.JsThisRef x, JsContext ctx) {
-    answer = 17; // primary
-    return false;
-  }
+    @Override
+    public boolean visit(JsFor x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 
-  @Override
-  public boolean visit(JsThrow x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
+    @Override
+    public boolean visit(JsForIn x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 
-  @Override
-  public boolean visit(JsTry x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
+    @Override
+    public boolean visit(JsFunction x, JsContext ctx) {
+        answer = 17; // primary
+        return false;
+    }
 
-  @Override
-  public boolean visit(JsVar x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
+    @Override
+    public boolean visit(JsIf x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 
-  @Override
-  public boolean visit(JsVars x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
+    @Override
+    public boolean visit(JsInvocation x, JsContext ctx) {
+        answer = 16;
+        return false;
+    }
 
-  @Override
-  public boolean visit(JsWhile x, JsContext ctx) {
-    throw new RuntimeException("Only expressions have precedence.");
-  }
+    @Override
+    public boolean visit(JsLabel x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
+
+    @Override
+    public boolean visit(JsNameRef x, JsContext ctx) {
+        if (x.isLeaf()) {
+            answer = 17; // primary
+        }
+        else {
+            answer = 16; // property access
+        }
+        return false;
+    }
+
+    @Override
+    public boolean visit(JsNew x, JsContext ctx) {
+        answer = PRECEDENCE_NEW;
+        return false;
+    }
+
+    @Override
+    public void visit(JsNullLiteral x, JsContext ctx) {
+        answer = 17; // primary
+    }
+
+    @Override
+    public void visit(JsNumberLiteral.JsIntLiteral x, JsContext ctx) {
+        answer = 17; // primary
+    }
+
+    @Override
+    public void visit(JsNumberLiteral.JsDoubleLiteral x, JsContext ctx) {
+        answer = 17; // primary
+    }
+
+    @Override
+    public boolean visit(JsObjectLiteral x, JsContext ctx) {
+        answer = 17; // primary
+        return false;
+    }
+
+    @Override
+    public boolean visit(JsParameter x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
+
+    @Override
+    public boolean visit(JsPostfixOperation x, JsContext ctx) {
+        answer = x.getOperator().getPrecedence();
+        return false;
+    }
+
+    @Override
+    public boolean visit(JsPrefixOperation x, JsContext ctx) {
+        answer = x.getOperator().getPrecedence();
+        return false;
+    }
+
+    @Override
+    public boolean visit(JsProgram x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
+
+    @Override
+    public boolean visit(JsPropertyInitializer x, JsContext ctx) {
+        answer = 17; // primary
+        return false;
+    }
+
+    @Override
+    public void visit(JsRegExp x, JsContext ctx) {
+        answer = 17; // primary
+    }
+
+    @Override
+    public boolean visit(JsReturn x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
+
+    @Override
+    public void visit(JsStringLiteral x, JsContext ctx) {
+        answer = 17; // primary
+    }
+
+    @Override
+    public boolean visit(JsSwitch x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
+
+    @Override
+    public boolean visit(JsLiteral.JsThisRef x, JsContext ctx) {
+        answer = 17; // primary
+        return false;
+    }
+
+    @Override
+    public boolean visit(JsThrow x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
+
+    @Override
+    public boolean visit(JsTry x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
+
+    @Override
+    public boolean visit(JsVar x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
+
+    @Override
+    public boolean visit(JsVars x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
+
+    @Override
+    public boolean visit(JsWhile x, JsContext ctx) {
+        throw new RuntimeException("Only expressions have precedence.");
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/JsRequiresSemiVisitor.java b/src/com/google/dart/compiler/backend/js/JsRequiresSemiVisitor.java
index b2205d3160b..7bc6e95da5a 100644
--- a/src/com/google/dart/compiler/backend/js/JsRequiresSemiVisitor.java
+++ b/src/com/google/dart/compiler/backend/js/JsRequiresSemiVisitor.java
@@ -55,11 +55,6 @@ public class JsRequiresSemiVisitor extends JsVisitor {
     return false;
   }
 
-  @Override
-  public boolean visit(JsEmpty x, JsContext ctx) {
-    return false;
-  }
-
   @Override
   public boolean visit(JsExpressionStatement x, JsContext ctx) {
     return false;
diff --git a/src/com/google/dart/compiler/backend/js/JsToStringGenerationVisitor.java b/src/com/google/dart/compiler/backend/js/JsToStringGenerationVisitor.java
index 6476775a129..b4c0bb5cf4d 100644
--- a/src/com/google/dart/compiler/backend/js/JsToStringGenerationVisitor.java
+++ b/src/com/google/dart/compiler/backend/js/JsToStringGenerationVisitor.java
@@ -323,7 +323,7 @@ public class JsToStringGenerationVisitor extends JsVisitor {
     public boolean visit(JsCase x, JsContext ctx) {
         p.print(CHARS_CASE);
         space();
-        accept(x.getCaseExpr());
+        accept(x.getCaseExpression());
         _colon();
         newlineOpt();
 
@@ -450,8 +450,7 @@ public class JsToStringGenerationVisitor extends JsVisitor {
     }
 
     @Override
-    public boolean visit(JsEmpty x, JsContext ctx) {
-        return false;
+    public void visit(JsEmpty x, JsContext ctx) {
     }
 
     @Override
@@ -650,12 +649,12 @@ public class JsToStringGenerationVisitor extends JsVisitor {
         p.print(CHARS_NEW);
         space();
 
-        JsExpression ctorExpr = x.getConstructorExpression();
-        boolean needsParens = JsConstructExpressionVisitor.exec(ctorExpr);
+        JsExpression constructorExpression = x.getConstructorExpression();
+        boolean needsParens = JsConstructExpressionVisitor.exec(constructorExpression);
         if (needsParens) {
             leftParen();
         }
-        accept(ctorExpr);
+        accept(constructorExpression);
         if (needsParens) {
             rightParen();
         }
@@ -668,21 +667,18 @@ public class JsToStringGenerationVisitor extends JsVisitor {
     }
 
     @Override
-    public boolean visit(JsNullLiteral x, JsContext ctx) {
+    public void visit(JsNullLiteral x, JsContext ctx) {
         p.print(CHARS_NULL);
-        return false;
     }
 
     @Override
-    public boolean visit(JsIntLiteral x, JsContext ctx) {
+    public void visit(JsIntLiteral x, JsContext ctx) {
         p.print(x.value);
-        return false;
     }
 
     @Override
-    public boolean visit(JsDoubleLiteral x, JsContext ctx) {
+    public void visit(JsDoubleLiteral x, JsContext ctx) {
         p.print(x.value);
-        return false;
     }
 
     @Override
@@ -788,7 +784,7 @@ public class JsToStringGenerationVisitor extends JsVisitor {
     }
 
     @Override
-    public boolean visit(JsRegExp x, JsContext ctx) {
+    public void visit(JsRegExp x, JsContext ctx) {
         _slash();
         p.print(x.getPattern());
         _slash();
@@ -796,13 +792,12 @@ public class JsToStringGenerationVisitor extends JsVisitor {
         if (flags != null) {
             p.print(flags);
         }
-        return false;
     }
 
     @Override
     public boolean visit(JsReturn x, JsContext ctx) {
         p.print(CHARS_RETURN);
-        JsExpression expr = x.getExpr();
+        JsExpression expr = x.getExpression();
         if (expr != null) {
             space();
             accept(expr);
@@ -811,9 +806,8 @@ public class JsToStringGenerationVisitor extends JsVisitor {
     }
 
     @Override
-    public boolean visit(JsStringLiteral x, JsContext ctx) {
+    public void visit(JsStringLiteral x, JsContext ctx) {
         p.print(javaScriptString(x.getValue()));
-        return false;
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/ChameleonJsExpression.java b/src/com/google/dart/compiler/backend/js/ast/ChameleonJsExpression.java
index 65047589936..d926ef6ec46 100644
--- a/src/com/google/dart/compiler/backend/js/ast/ChameleonJsExpression.java
+++ b/src/com/google/dart/compiler/backend/js/ast/ChameleonJsExpression.java
@@ -1,7 +1,5 @@
 package com.google.dart.compiler.backend.js.ast;
 
-import com.google.dart.compiler.common.SourceInfo;
-
 public class ChameleonJsExpression implements JsExpression {
     private JsExpression expression;
 
@@ -47,8 +45,13 @@ public class ChameleonJsExpression implements JsExpression {
     }
 
     @Override
-    public void traverse(JsVisitor visitor, JsContext context) {
-        expression.traverse(visitor, context);
+    public void accept(JsVisitor visitor, JsContext context) {
+        expression.accept(visitor, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        expression.acceptChildren(visitor, context);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/HasArguments.java b/src/com/google/dart/compiler/backend/js/ast/HasArguments.java
index 814189f2846..29b12859174 100644
--- a/src/com/google/dart/compiler/backend/js/ast/HasArguments.java
+++ b/src/com/google/dart/compiler/backend/js/ast/HasArguments.java
@@ -10,6 +10,5 @@ import java.util.List;
  * Implemented by JavaScript objects that accept arguments.
  */
 public interface HasArguments extends JsExpression {
-
   List<JsExpression> getArguments();
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsArrayAccess.java b/src/com/google/dart/compiler/backend/js/ast/JsArrayAccess.java
index ec08121c755..3e668bf3fe1 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsArrayAccess.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsArrayAccess.java
@@ -8,60 +8,62 @@ package com.google.dart.compiler.backend.js.ast;
  * Represents a javascript expression for array access.
  */
 public final class JsArrayAccess extends JsExpressionImpl {
-  private JsExpression arrayExpression;
-  private JsExpression indexExpression;
+    private JsExpression arrayExpression;
+    private JsExpression indexExpression;
 
-  public JsArrayAccess() {
-    super();
-  }
-
-  public JsArrayAccess(JsExpression arrayExpression, JsExpression indexExpression) {
-    this.arrayExpression = arrayExpression;
-    this.indexExpression = indexExpression;
-  }
-
-  public JsExpression getArrayExpression() {
-    return arrayExpression;
-  }
-
-  public JsExpression getIndexExpression() {
-    return indexExpression;
-  }
-
-  @Override
-  public boolean hasSideEffects() {
-    return arrayExpression.hasSideEffects() || indexExpression.hasSideEffects();
-  }
-
-  @Override
-  public boolean isDefinitelyNotNull() {
-    return false;
-  }
-
-  @Override
-  public boolean isDefinitelyNull() {
-    return false;
-  }
-
-  public void setArrayExpression(JsExpression arrayExpression) {
-    this.arrayExpression = arrayExpression;
-  }
-
-  public void setIndexExpression(JsExpression indexExpression) {
-    this.indexExpression = indexExpression;
-  }
-
-  @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    if (v.visit(this, context)) {
-      arrayExpression = v.accept(arrayExpression);
-      indexExpression = v.accept(indexExpression);
+    public JsArrayAccess() {
+        super();
     }
-    v.endVisit(this, context);
-  }
 
-  @Override
-  public NodeKind getKind() {
-    return NodeKind.ARRAY_ACCESS;
-  }
+    public JsArrayAccess(JsExpression arrayExpression, JsExpression indexExpression) {
+        this.arrayExpression = arrayExpression;
+        this.indexExpression = indexExpression;
+    }
+
+    public JsExpression getArrayExpression() {
+        return arrayExpression;
+    }
+
+    public JsExpression getIndexExpression() {
+        return indexExpression;
+    }
+
+    @Override
+    public boolean hasSideEffects() {
+        return arrayExpression.hasSideEffects() || indexExpression.hasSideEffects();
+    }
+
+    @Override
+    public boolean isDefinitelyNotNull() {
+        return false;
+    }
+
+    @Override
+    public boolean isDefinitelyNull() {
+        return false;
+    }
+
+    public void setArrayExpression(JsExpression arrayExpression) {
+        this.arrayExpression = arrayExpression;
+    }
+
+    public void setIndexExpression(JsExpression indexExpression) {
+        this.indexExpression = indexExpression;
+    }
+
+    @Override
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        arrayExpression = visitor.accept(arrayExpression);
+        indexExpression = visitor.accept(indexExpression);
+    }
+
+    @Override
+    public NodeKind getKind() {
+        return NodeKind.ARRAY_ACCESS;
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsArrayLiteral.java b/src/com/google/dart/compiler/backend/js/ast/JsArrayLiteral.java
index 5c1a8bcdb00..50603f0bfbc 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsArrayLiteral.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsArrayLiteral.java
@@ -57,11 +57,13 @@ public final class JsArrayLiteral extends JsLiteral {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            v.acceptWithInsertRemove(expressions);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        visitor.acceptWithInsertRemove(expressions);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsBinaryOperation.java b/src/com/google/dart/compiler/backend/js/ast/JsBinaryOperation.java
index 9b6327f74c0..aea44e2e35c 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsBinaryOperation.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsBinaryOperation.java
@@ -10,91 +10,82 @@ import org.jetbrains.annotations.Nullable;
  * Represents a JavaScript binary operation.
  */
 public final class JsBinaryOperation extends JsExpressionImpl {
-  private JsExpression arg1;
-  private JsExpression arg2;
-  private final JsBinaryOperator op;
+    private JsExpression arg1;
+    private JsExpression arg2;
+    private final JsBinaryOperator op;
 
-  public JsBinaryOperation(JsBinaryOperator op) {
-    this(op, null, null);
-  }
-
-  public JsBinaryOperation(JsBinaryOperator op, @Nullable JsExpression arg1, @Nullable JsExpression arg2) {
-    this.op = op;
-    this.arg1 = arg1;
-    this.arg2 = arg2;
-  }
-
-  public JsExpression getArg1() {
-    return arg1;
-  }
-
-  public JsExpression getArg2() {
-    return arg2;
-  }
-
-  public JsBinaryOperator getOperator() {
-    return op;
-  }
-
-  @Override
-  public boolean hasSideEffects() {
-    return op.isAssignment() || arg1.hasSideEffects() || arg2.hasSideEffects();
-  }
-
-  @Override
-  public boolean isDefinitelyNotNull() {
-    // Precarious coding, but none of these can have null results.
-    if (op.getPrecedence() > 5) {
-      return true;
+    public JsBinaryOperation(JsBinaryOperator op) {
+        this(op, null, null);
     }
-    if (op == JsBinaryOperator.OR) {
-      if (arg1 instanceof CanBooleanEval) {
-        if (((CanBooleanEval) arg1).isBooleanTrue()) {
-          assert arg1.isDefinitelyNotNull();
-          return true;
+
+    public JsBinaryOperation(JsBinaryOperator op, @Nullable JsExpression arg1, @Nullable JsExpression arg2) {
+        this.op = op;
+        this.arg1 = arg1;
+        this.arg2 = arg2;
+    }
+
+    public JsExpression getArg1() {
+        return arg1;
+    }
+
+    public JsExpression getArg2() {
+        return arg2;
+    }
+
+    public JsBinaryOperator getOperator() {
+        return op;
+    }
+
+    @Override
+    public boolean hasSideEffects() {
+        return op.isAssignment() || arg1.hasSideEffects() || arg2.hasSideEffects();
+    }
+
+    @Override
+    public boolean isDefinitelyNotNull() {
+        // Precarious coding, but none of these can have null results.
+        if (op.getPrecedence() > 5) {
+            return true;
         }
-      }
-    }
-    // AND and OR can return nulls
-    if (op.isAssignment()) {
-      if (op == JsBinaryOperator.ASG) {
-        return arg2.isDefinitelyNotNull();
-      } else {
-        // All other ASG's are math ops.
-        return true;
-      }
+        if (op == JsBinaryOperator.OR) {
+            if (arg1 instanceof CanBooleanEval) {
+                if (((CanBooleanEval) arg1).isBooleanTrue()) {
+                    assert arg1.isDefinitelyNotNull();
+                    return true;
+                }
+            }
+        }
+        // AND and OR can return nulls
+        if (op.isAssignment()) {
+            return op != JsBinaryOperator.ASG || arg2.isDefinitelyNotNull();
+        }
+
+        return op == JsBinaryOperator.COMMA && arg2.isDefinitelyNotNull();
     }
 
-    if (op == JsBinaryOperator.COMMA) {
-      return arg2.isDefinitelyNotNull();
+    @Override
+    public boolean isDefinitelyNull() {
+        return op == JsBinaryOperator.AND && arg1.isDefinitelyNull();
     }
 
-    return false;
-  }
-
-  @Override
-  public boolean isDefinitelyNull() {
-    if (op == JsBinaryOperator.AND) {
-      return arg1.isDefinitelyNull();
+    @Override
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
     }
-    return false;
-  }
 
-  @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    if (v.visit(this, context)) {
-      if (op.isAssignment()) {
-        arg1 = v.acceptLvalue(arg1);
-      } else {
-        arg1 = v.accept(arg1);
-      }
-      arg2 = v.accept(arg2);
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        if (op.isAssignment()) {
+            arg1 = visitor.acceptLvalue(arg1);
+        }
+        else {
+            arg1 = visitor.accept(arg1);
+        }
+        arg2 = visitor.accept(arg2);
     }
-    v.endVisit(this, context);
-  }
 
-  @Override
-  public NodeKind getKind() {
-    return NodeKind.BINARY_OP;
-  }
+    @Override
+    public NodeKind getKind() {
+        return NodeKind.BINARY_OP;
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsBlock.java b/src/com/google/dart/compiler/backend/js/ast/JsBlock.java
index 633d88f72b2..7b6874df47c 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsBlock.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsBlock.java
@@ -44,11 +44,13 @@ public class JsBlock extends JsNodeImpl implements JsStatement {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            v.acceptWithInsertRemove(statements);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        visitor.acceptWithInsertRemove(statements);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsBreak.java b/src/com/google/dart/compiler/backend/js/ast/JsBreak.java
index 50a23c051e2..8932788e3fe 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsBreak.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsBreak.java
@@ -22,8 +22,7 @@ public final class JsBreak extends JsContinue {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
+    public void accept(JsVisitor v, JsContext context) {
         v.visit(this, context);
-        v.endVisit(this, context);
     }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsCase.java b/src/com/google/dart/compiler/backend/js/ast/JsCase.java
index e1598a509d6..feaaa5d847c 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsCase.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsCase.java
@@ -8,32 +8,33 @@ package com.google.dart.compiler.backend.js.ast;
  * Represents the JavaScript case statement.
  */
 public final class JsCase extends JsSwitchMember {
+    private JsExpression caseExpression;
 
-  private JsExpression caseExpr;
-
-  public JsCase() {
-    super();
-  }
-
-  public JsExpression getCaseExpr() {
-    return caseExpr;
-  }
-
-  public void setCaseExpr(JsExpression caseExpr) {
-    this.caseExpr = caseExpr;
-  }
-
-  @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    if (v.visit(this, context)) {
-      caseExpr = v.accept(caseExpr);
-      v.acceptWithInsertRemove(statements);
+    public JsCase() {
+        super();
     }
-    v.endVisit(this, context);
-  }
 
-  @Override
-  public NodeKind getKind() {
-    return NodeKind.CASE;
-  }
+    public JsExpression getCaseExpression() {
+        return caseExpression;
+    }
+
+    public void setCaseExpression(JsExpression caseExpression) {
+        this.caseExpression = caseExpression;
+    }
+
+    @Override
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        caseExpression = visitor.accept(caseExpression);
+        super.acceptChildren(visitor, context);
+    }
+
+    @Override
+    public NodeKind getKind() {
+        return NodeKind.CASE;
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsCatch.java b/src/com/google/dart/compiler/backend/js/ast/JsCatch.java
index 1d3846fa6f0..24a729051f8 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsCatch.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsCatch.java
@@ -9,58 +9,60 @@ package com.google.dart.compiler.backend.js.ast;
  */
 public class JsCatch extends JsNodeImpl implements HasCondition {
 
-  protected final JsCatchScope scope;
-  private JsBlock body;
-  private JsExpression condition;
-  private JsParameter param;
+    protected final JsCatchScope scope;
+    private JsBlock body;
+    private JsExpression condition;
+    private JsParameter param;
 
-  public JsCatch(JsScope parent, String ident) {
-    super();
-    assert (parent != null);
-    scope = new JsCatchScope(parent, ident);
-    param = new JsParameter(scope.findName(ident));
-  }
-
-  public JsBlock getBody() {
-    return body;
-  }
-
-  @Override
-  public JsExpression getCondition() {
-    return condition;
-  }
-
-  public JsParameter getParameter() {
-    return param;
-  }
-
-  public JsScope getScope() {
-    return scope;
-  }
-
-  public void setBody(JsBlock body) {
-    this.body = body;
-  }
-
-  @Override
-  public void setCondition(JsExpression condition) {
-    this.condition = condition;
-  }
-
-  @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    if (v.visit(this, context)) {
-      param = v.accept(param);
-      if (condition != null) {
-        condition = v.accept(condition);
-      }
-      body = v.accept(body);
+    public JsCatch(JsScope parent, String ident) {
+        super();
+        assert (parent != null);
+        scope = new JsCatchScope(parent, ident);
+        param = new JsParameter(scope.findName(ident));
     }
-    v.endVisit(this, context);
-  }
 
-  @Override
-  public NodeKind getKind() {
-    return NodeKind.CATCH;
-  }
+    public JsBlock getBody() {
+        return body;
+    }
+
+    @Override
+    public JsExpression getCondition() {
+        return condition;
+    }
+
+    public JsParameter getParameter() {
+        return param;
+    }
+
+    public JsScope getScope() {
+        return scope;
+    }
+
+    public void setBody(JsBlock body) {
+        this.body = body;
+    }
+
+    @Override
+    public void setCondition(JsExpression condition) {
+        this.condition = condition;
+    }
+
+    @Override
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        param = visitor.accept(param);
+        if (condition != null) {
+            condition = visitor.accept(condition);
+        }
+        body = visitor.accept(body);
+    }
+
+    @Override
+    public NodeKind getKind() {
+        return NodeKind.CATCH;
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsConditional.java b/src/com/google/dart/compiler/backend/js/ast/JsConditional.java
index 2bf2dda635e..7c82a97726d 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsConditional.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsConditional.java
@@ -61,13 +61,15 @@ public final class JsConditional extends JsExpressionImpl {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            testExpr = v.accept(testExpr);
-            thenExpr = v.accept(thenExpr);
-            elseExpr = v.accept(elseExpr);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        testExpr = visitor.accept(testExpr);
+        thenExpr = visitor.accept(thenExpr);
+        elseExpr = visitor.accept(elseExpr);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsContext.java b/src/com/google/dart/compiler/backend/js/ast/JsContext.java
index 15371c8ec41..35b8c74769e 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsContext.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsContext.java
@@ -14,13 +14,13 @@ public interface JsContext {
 
   boolean canRemove();
 
-  void insertAfter(JsVisitable node);
+  void insertAfter(JsNode node);
 
-  void insertBefore(JsVisitable node);
+  void insertBefore(JsNode node);
 
   boolean isLvalue();
 
   void removeMe();
 
-  void replaceMe(JsVisitable node);
+  void replaceMe(JsNode node);
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsContinue.java b/src/com/google/dart/compiler/backend/js/ast/JsContinue.java
index dcec38018f7..bd7aebbf5ca 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsContinue.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsContinue.java
@@ -6,9 +6,6 @@ package com.google.dart.compiler.backend.js.ast;
 
 import org.jetbrains.annotations.Nullable;
 
-/**
- * Represents the JavaScript continue statement.
- */
 public class JsContinue extends JsNodeImpl implements JsStatement {
     protected final String label;
 
@@ -26,9 +23,13 @@ public class JsContinue extends JsNodeImpl implements JsStatement {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
+    public void accept(JsVisitor v, JsContext context) {
         v.visit(this, context);
-        v.endVisit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsDebugger.java b/src/com/google/dart/compiler/backend/js/ast/JsDebugger.java
index 45db05149a8..6d48cef820e 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsDebugger.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsDebugger.java
@@ -13,12 +13,16 @@ public class JsDebugger extends JsNodeImpl implements JsStatement {
   }
 
   @Override
-  public void traverse(JsVisitor v, JsContext context) {
+  public void accept(JsVisitor v, JsContext context) {
     v.visit(this, context);
-    v.endVisit(this, context);
   }
 
-  @Override
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+
+    }
+
+    @Override
   public NodeKind getKind() {
     return NodeKind.DEBUGGER;
   }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsDefault.java b/src/com/google/dart/compiler/backend/js/ast/JsDefault.java
index b59dca783a9..227228df2e1 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsDefault.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsDefault.java
@@ -8,17 +8,9 @@ package com.google.dart.compiler.backend.js.ast;
  * Represents the default option in a JavaScript swtich statement.
  */
 public final class JsDefault extends JsSwitchMember {
-
-  public JsDefault() {
-    super();
-  }
-
   @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    if (v.visit(this, context)) {
-      v.acceptWithInsertRemove(statements);
-    }
-    v.endVisit(this, context);
+  public void accept(JsVisitor v, JsContext context) {
+    v.visit(this, context);
   }
 
   @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsDoWhile.java b/src/com/google/dart/compiler/backend/js/ast/JsDoWhile.java
index 10253c39b55..e860a699f8b 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsDoWhile.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsDoWhile.java
@@ -21,11 +21,10 @@ public class JsDoWhile extends JsWhile {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
+    public void accept(JsVisitor v, JsContext context) {
         if (v.visit(this, context)) {
             condition = v.accept(condition);
             body = v.accept(body);
         }
-        v.endVisit(this, context);
     }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsDocComment.java b/src/com/google/dart/compiler/backend/js/ast/JsDocComment.java
index 909fd225846..b432b45a6d1 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsDocComment.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsDocComment.java
@@ -28,10 +28,15 @@ public class JsDocComment extends JsExpressionImpl {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
+    public void accept(JsVisitor v, JsContext context) {
         v.visit(this, context);
     }
 
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+
+    }
+
     @Override
     public boolean hasSideEffects() {
         return false;
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsEmpty.java b/src/com/google/dart/compiler/backend/js/ast/JsEmpty.java
index 3ecc8f1d3bc..31ab7908cd0 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsEmpty.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsEmpty.java
@@ -4,22 +4,21 @@
 
 package com.google.dart.compiler.backend.js.ast;
 
-/**
- * Represents an empty statement in JavaScript.
- */
 public class JsEmpty extends JsNodeImpl implements JsStatement {
-  // Interned by JsProgram
-  JsEmpty() {
-  }
+    JsEmpty() {
+    }
 
-  @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    v.visit(this, context);
-    v.endVisit(this, context);
-  }
+    @Override
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
 
-  @Override
-  public NodeKind getKind() {
-    return NodeKind.EMPTY;
-  }
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+    }
+
+    @Override
+    public NodeKind getKind() {
+        return NodeKind.EMPTY;
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsExpression.java b/src/com/google/dart/compiler/backend/js/ast/JsExpression.java
index def914d6a70..5cbc2bd4284 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsExpression.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsExpression.java
@@ -2,7 +2,7 @@ package com.google.dart.compiler.backend.js.ast;
 
 import com.google.dart.compiler.common.HasSourceInfo;
 
-public interface JsExpression extends JsNode, HasSourceInfo, JsVisitable {
+public interface JsExpression extends JsNode, HasSourceInfo {
     /**
      * Determines whether the expression can cause side effects.
      */
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsExpressionImpl.java b/src/com/google/dart/compiler/backend/js/ast/JsExpressionImpl.java
index 2e46db4bef9..8ae907a92ad 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsExpressionImpl.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsExpressionImpl.java
@@ -4,6 +4,8 @@
 
 package com.google.dart.compiler.backend.js.ast;
 
+import java.util.List;
+
 abstract class JsExpressionImpl extends JsNodeImpl implements JsExpression {
     protected JsExpressionImpl() {
     }
@@ -24,4 +26,17 @@ abstract class JsExpressionImpl extends JsNodeImpl implements JsExpression {
     public JsStatement makeStmt() {
         return new JsExpressionStatement(this);
     }
+
+    protected abstract static class JsExpressionHasArguments extends JsExpressionImpl implements HasArguments {
+        protected final List<JsExpression> arguments;
+
+        public JsExpressionHasArguments(List<JsExpression> arguments) {
+            this.arguments = arguments;
+        }
+
+        @Override
+        public List<JsExpression> getArguments() {
+            return arguments;
+        }
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsExpressionStatement.java b/src/com/google/dart/compiler/backend/js/ast/JsExpressionStatement.java
index ba5a1b6f26f..deb413ee43d 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsExpressionStatement.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsExpressionStatement.java
@@ -16,11 +16,13 @@ public final class JsExpressionStatement extends AbstractNode implements JsState
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            expression = v.accept(expression);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        expression = visitor.accept(expression);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsFor.java b/src/com/google/dart/compiler/backend/js/ast/JsFor.java
index 2eb846e6b6f..d76f7ec50f9 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsFor.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsFor.java
@@ -71,27 +71,29 @@ public class JsFor extends JsNodeImpl implements JsStatement {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            assert (!(initExpression != null && initVars != null));
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
 
-            if (initExpression != null) {
-                initExpression = v.accept(initExpression);
-            }
-            else if (initVars != null) {
-                initVars = v.accept(initVars);
-            }
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        assert (!(initExpression != null && initVars != null));
 
-            if (condition != null) {
-                condition = v.accept(condition);
-            }
-
-            if (incrementExpression != null) {
-                incrementExpression = v.accept(incrementExpression);
-            }
-            body = v.accept(body);
+        if (initExpression != null) {
+            initExpression = visitor.accept(initExpression);
         }
-        v.endVisit(this, context);
+        else if (initVars != null) {
+            initVars = visitor.accept(initVars);
+        }
+
+        if (condition != null) {
+            condition = visitor.accept(condition);
+        }
+
+        if (incrementExpression != null) {
+            incrementExpression = visitor.accept(incrementExpression);
+        }
+        body = visitor.accept(body);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsForIn.java b/src/com/google/dart/compiler/backend/js/ast/JsForIn.java
index a0e31f4af5b..7fa3edd4fa9 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsForIn.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsForIn.java
@@ -8,64 +8,67 @@ package com.google.dart.compiler.backend.js.ast;
  * Represents a JavaScript for..in statement.
  */
 public class JsForIn extends JsNodeImpl implements JsStatement {
+    private JsStatement body;
+    private JsExpression iterExpr;
+    private JsExpression objExpr;
 
-  private JsStatement body;
-  private JsExpression iterExpr;
-  private JsExpression objExpr;
+    // Optional: the name of a new iterator variable to introduce
+    private final JsName iterVarName;
 
-  // Optional: the name of a new iterator variable to introduce
-  private final JsName iterVarName;
-
-  public JsForIn() {
-    this(null);
-  }
-
-  public JsForIn(JsName iterVarName) {
-    this.iterVarName = iterVarName;
-  }
-
-  public JsStatement getBody() {
-    return body;
-  }
-
-  public JsExpression getIterExpr() {
-    return iterExpr;
-  }
-
-  public JsName getIterVarName() {
-    return iterVarName;
-  }
-
-  public JsExpression getObjExpr() {
-    return objExpr;
-  }
-
-  public void setBody(JsStatement body) {
-    this.body = body;
-  }
-
-  public void setIterExpr(JsExpression iterExpr) {
-    this.iterExpr = iterExpr;
-  }
-
-  public void setObjExpr(JsExpression objExpr) {
-    this.objExpr = objExpr;
-  }
-
-  @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    if (v.visit(this, context)) {
-      if (iterExpr != null) {
-        iterExpr = v.acceptLvalue(iterExpr);
-      }
-      objExpr = v.accept(objExpr);
-      body = v.accept(body);
+    public JsForIn() {
+        this(null);
     }
-    v.endVisit(this, context);
-  }
 
-  @Override
-  public NodeKind getKind() {
-    return NodeKind.FOR_IN;
-  }
+    public JsForIn(JsName iterVarName) {
+        this.iterVarName = iterVarName;
+    }
+
+    public JsStatement getBody() {
+        return body;
+    }
+
+    public JsExpression getIterExpr() {
+        return iterExpr;
+    }
+
+    public JsName getIterVarName() {
+        return iterVarName;
+    }
+
+    public JsExpression getObjExpr() {
+        return objExpr;
+    }
+
+    public void setBody(JsStatement body) {
+        this.body = body;
+    }
+
+    public void setIterExpr(JsExpression iterExpr) {
+        this.iterExpr = iterExpr;
+    }
+
+    public void setObjExpr(JsExpression objExpr) {
+        this.objExpr = objExpr;
+    }
+
+    @Override
+    public void accept(JsVisitor v, JsContext context) {
+        if (v.visit(this, context)) {
+
+        }
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        if (iterExpr != null) {
+            iterExpr = visitor.acceptLvalue(iterExpr);
+        }
+        objExpr = visitor.accept(objExpr);
+        body = visitor.accept(body);
+    }
+
+    @Override
+    public NodeKind getKind() {
+        return NodeKind.FOR_IN;
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsFunction.java b/src/com/google/dart/compiler/backend/js/ast/JsFunction.java
index 1d4bd4da308..ae1a1ef85b2 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsFunction.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsFunction.java
@@ -90,12 +90,14 @@ public final class JsFunction extends JsLiteral implements HasName {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            v.acceptWithInsertRemove(params);
-            body = v.accept(body);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        visitor.acceptWithInsertRemove(params);
+                    body = visitor.accept(body);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsIf.java b/src/com/google/dart/compiler/backend/js/ast/JsIf.java
index ad75b9b2a2d..d7e93226d57 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsIf.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsIf.java
@@ -51,15 +51,17 @@ public final class JsIf extends JsNodeImpl implements JsStatement {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            ifExpression = v.accept(ifExpression);
-            thenStatement = v.accept(thenStatement);
-            if (elseStatement != null) {
-                elseStatement = v.accept(elseStatement);
-            }
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        ifExpression = visitor.accept(ifExpression);
+                    thenStatement = visitor.accept(thenStatement);
+                    if (elseStatement != null) {
+                        elseStatement = visitor.accept(elseStatement);
+                    }
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsInvocation.java b/src/com/google/dart/compiler/backend/js/ast/JsInvocation.java
index 96b9f8e5cec..3c9bc107e87 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsInvocation.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsInvocation.java
@@ -13,17 +13,16 @@ import java.util.List;
 /**
  * Represents a JavaScript invocation.
  */
-public final class JsInvocation extends JsExpressionImpl implements HasArguments {
-    private final List<JsExpression> arguments;
+public final class JsInvocation extends JsExpressionImpl.JsExpressionHasArguments {
     private JsExpression qualifier;
 
     public JsInvocation() {
-        arguments = new SmartList<JsExpression>();
+        super(new SmartList<JsExpression>());
     }
 
     public JsInvocation(JsExpression qualifier, List<JsExpression> arguments) {
+        super(arguments);
         this.qualifier = qualifier;
-        this.arguments = arguments;
     }
 
     public JsInvocation(JsExpression qualifier, JsExpression arg) {
@@ -68,12 +67,14 @@ public final class JsInvocation extends JsExpressionImpl implements HasArguments
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            qualifier = v.accept(qualifier);
-            v.acceptList(arguments);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        qualifier = visitor.accept(qualifier);
+        visitor.acceptList(arguments);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsLabel.java b/src/com/google/dart/compiler/backend/js/ast/JsLabel.java
index 3dbe28bc361..b4dd4ca2355 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsLabel.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsLabel.java
@@ -42,12 +42,14 @@ public class JsLabel extends JsNodeImpl implements JsStatement, HasName {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            statement = v.accept(statement);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
     }
+    
+    @Override
+        public void acceptChildren(JsVisitor visitor, JsContext context) {
+        statement = visitor.accept(statement);
+        }
 
     @Override
     public NodeKind getKind() {
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsLiteral.java b/src/com/google/dart/compiler/backend/js/ast/JsLiteral.java
index f8cc734d453..bc9eee97cd1 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsLiteral.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsLiteral.java
@@ -43,9 +43,8 @@ public abstract class JsLiteral extends JsExpressionImpl implements CanBooleanEv
         }
 
         @Override
-        public void traverse(JsVisitor v, JsContext context) {
+        public void accept(JsVisitor v, JsContext context) {
             v.visit(this, context);
-            v.endVisit(this, context);
         }
 
         @Override
@@ -87,9 +86,8 @@ public abstract class JsLiteral extends JsExpressionImpl implements CanBooleanEv
       }
 
       @Override
-      public void traverse(JsVisitor v, JsContext context) {
+      public void accept(JsVisitor v, JsContext context) {
         v.visit(this, context);
-        v.endVisit(this, context);
       }
 
       @Override
@@ -97,4 +95,26 @@ public abstract class JsLiteral extends JsExpressionImpl implements CanBooleanEv
         return NodeKind.BOOLEAN;
       }
     }
+
+    /**
+     * A JavaScript string literal expression.
+     */
+    public abstract static class JsValueLiteral extends JsLiteral {
+        protected JsValueLiteral() {
+        }
+
+        @Override
+        public final boolean hasSideEffects() {
+            return false;
+        }
+
+        @Override
+        public final boolean isLeaf() {
+            return true;
+        }
+
+        @Override
+        public void acceptChildren(JsVisitor visitor, JsContext context) {
+        }
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsNameRef.java b/src/com/google/dart/compiler/backend/js/ast/JsNameRef.java
index 1f12ed8c628..c877630db1c 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsNameRef.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsNameRef.java
@@ -56,14 +56,7 @@ public final class JsNameRef extends JsExpressionImpl implements CanBooleanEval,
 
     @Override
     public boolean hasSideEffects() {
-        if (qualifier == null) {
-            return false;
-        }
-        if (!qualifier.isDefinitelyNotNull()) {
-            // Could trigger NPE.
-            return true;
-        }
-        return qualifier.hasSideEffects();
+        return qualifier != null && (!qualifier.isDefinitelyNotNull() || qualifier.hasSideEffects());
     }
 
     @Override
@@ -83,25 +76,17 @@ public final class JsNameRef extends JsExpressionImpl implements CanBooleanEval,
 
     @Override
     public boolean isDefinitelyNull() {
-        if (name != null) {
-            return (JsLiteral.UNDEFINED.getName() == name);
-        }
-        return false;
+        return name != null && (JsLiteral.UNDEFINED.getName() == name);
     }
 
     @Override
     public boolean isLeaf() {
-        if (qualifier == null) {
-            return true;
-        }
-        else {
-            return false;
-        }
+        return qualifier == null;
     }
 
     public void resolve(JsName name) {
         this.name = name;
-        this.ident = null;
+        ident = null;
     }
 
     public void setQualifier(JsExpression qualifier) {
@@ -109,13 +94,15 @@ public final class JsNameRef extends JsExpressionImpl implements CanBooleanEval,
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            if (qualifier != null) {
-                qualifier = v.accept(qualifier);
-            }
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        if (qualifier != null) {
+                        qualifier = visitor.accept(qualifier);
+                    }
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsNew.java b/src/com/google/dart/compiler/backend/js/ast/JsNew.java
index c65bebbde66..dac28938a62 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsNew.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsNew.java
@@ -8,29 +8,20 @@ import com.intellij.util.SmartList;
 
 import java.util.List;
 
-/**
- * Represents the JavaScript new expression.
- */
-public final class JsNew extends JsExpressionImpl implements HasArguments {
-    private final List<JsExpression> arguments;
-    private JsExpression ctorExpression;
+public final class JsNew extends JsExpressionImpl.JsExpressionHasArguments {
+    private JsExpression constructorExpression;
 
-    public JsNew(JsExpression ctorExpression) {
-        this(ctorExpression, new SmartList<JsExpression>());
+    public JsNew(JsExpression constructorExpression) {
+        this(constructorExpression, new SmartList<JsExpression>());
     }
 
-    public JsNew(JsExpression ctorExpression, List<JsExpression> arguments) {
-        this.ctorExpression = ctorExpression;
-        this.arguments = arguments;
-    }
-
-    @Override
-    public List<JsExpression> getArguments() {
-        return arguments;
+    public JsNew(JsExpression constructorExpression, List<JsExpression> arguments) {
+        super(arguments);
+        this.constructorExpression = constructorExpression;
     }
 
     public JsExpression getConstructorExpression() {
-        return ctorExpression;
+        return constructorExpression;
     }
 
     @Override
@@ -51,12 +42,14 @@ public final class JsNew extends JsExpressionImpl implements HasArguments {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            ctorExpression = v.accept(ctorExpression);
-            v.acceptList(arguments);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        constructorExpression = visitor.accept(constructorExpression);
+        visitor.acceptList(arguments);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsNode.java b/src/com/google/dart/compiler/backend/js/ast/JsNode.java
index 78e78af6434..83fcb376af5 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsNode.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsNode.java
@@ -4,6 +4,16 @@
 
 package com.google.dart.compiler.backend.js.ast;
 
-public interface JsNode extends JsVisitable {
+public interface JsNode {
     NodeKind getKind();
+
+    /**
+     * Causes this object to have the visitor visit itself and its children.
+     *
+     * @param visitor the visitor that should traverse this node
+     * @param context the context of an existing traversal
+     */
+    void accept(JsVisitor visitor, JsContext context);
+
+    void acceptChildren(JsVisitor visitor, JsContext context);
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsNodeImpl.java b/src/com/google/dart/compiler/backend/js/ast/JsNodeImpl.java
index 164300c68e4..b41e793dd4a 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsNodeImpl.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsNodeImpl.java
@@ -1,7 +1,5 @@
 package com.google.dart.compiler.backend.js.ast;
 
-import com.google.dart.compiler.common.SourceInfo;
-
 abstract class JsNodeImpl extends AbstractNode {
     private Object sourceInfo;
 
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsNullLiteral.java b/src/com/google/dart/compiler/backend/js/ast/JsNullLiteral.java
index 028760e4c0d..3974b1a5965 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsNullLiteral.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsNullLiteral.java
@@ -4,7 +4,7 @@
 
 package com.google.dart.compiler.backend.js.ast;
 
-public final class JsNullLiteral extends JsValueLiteral {
+public final class JsNullLiteral extends JsLiteral.JsValueLiteral {
     JsNullLiteral() {
     }
 
@@ -29,9 +29,8 @@ public final class JsNullLiteral extends JsValueLiteral {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
+    public void accept(JsVisitor v, JsContext context) {
         v.visit(this, context);
-        v.endVisit(this, context);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsNumberLiteral.java b/src/com/google/dart/compiler/backend/js/ast/JsNumberLiteral.java
index 8d47eca2dcf..8df65c40b7e 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsNumberLiteral.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsNumberLiteral.java
@@ -4,7 +4,7 @@
 
 package com.google.dart.compiler.backend.js.ast;
 
-public abstract class JsNumberLiteral extends JsValueLiteral {
+public abstract class JsNumberLiteral extends JsLiteral.JsValueLiteral {
     @Override
     public boolean isDefinitelyNotNull() {
         return true;
@@ -38,9 +38,8 @@ public abstract class JsNumberLiteral extends JsValueLiteral {
         }
 
         @Override
-        public void traverse(JsVisitor v, JsContext context) {
+        public void accept(JsVisitor v, JsContext context) {
             v.visit(this, context);
-            v.endVisit(this, context);
         }
 
         public String toString() {
@@ -66,9 +65,8 @@ public abstract class JsNumberLiteral extends JsValueLiteral {
         }
 
         @Override
-        public void traverse(JsVisitor v, JsContext context) {
+        public void accept(JsVisitor v, JsContext context) {
             v.visit(this, context);
-            v.endVisit(this, context);
         }
 
         public String toString() {
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsObjectLiteral.java b/src/com/google/dart/compiler/backend/js/ast/JsObjectLiteral.java
index f1ef5b54bfd..bbae493479a 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsObjectLiteral.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsObjectLiteral.java
@@ -69,11 +69,13 @@ public final class JsObjectLiteral extends JsLiteral {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            v.acceptWithInsertRemove(properties);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        visitor.acceptWithInsertRemove(properties);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsParameter.java b/src/com/google/dart/compiler/backend/js/ast/JsParameter.java
index 323646468c6..5d87432ce7f 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsParameter.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsParameter.java
@@ -10,30 +10,34 @@ import com.google.dart.compiler.common.Symbol;
  * A JavaScript parameter.
  */
 public final class JsParameter extends JsNodeImpl implements HasName {
-  private final JsName name;
+    private final JsName name;
 
-  public JsParameter(JsName name) {
-    this.name = name;
-  }
+    public JsParameter(JsName name) {
+        this.name = name;
+    }
 
-  @Override
-  public JsName getName() {
-    return name;
-  }
+    @Override
+    public JsName getName() {
+        return name;
+    }
 
-  @Override
-  public Symbol getSymbol() {
-    return name;
-  }
+    @Override
+    public Symbol getSymbol() {
+        return name;
+    }
 
-  @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    v.visit(this, context);
-    v.endVisit(this, context);
-  }
+    @Override
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
 
-  @Override
-  public NodeKind getKind() {
-    return NodeKind.PARAMETER;
-  }
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+
+    }
+
+    @Override
+    public NodeKind getKind() {
+        return NodeKind.PARAMETER;
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsPostfixOperation.java b/src/com/google/dart/compiler/backend/js/ast/JsPostfixOperation.java
index d32565dfc0b..177b6f79b60 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsPostfixOperation.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsPostfixOperation.java
@@ -28,11 +28,8 @@ public final class JsPostfixOperation extends JsUnaryOperation {
   }
 
   @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    if (v.visit(this, context)) {
-      super.traverse(v, context);
-    }
-    v.endVisit(this, context);
+  public void accept(JsVisitor v, JsContext context) {
+    v.visit(this, context);
   }
 
   @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsPrefixOperation.java b/src/com/google/dart/compiler/backend/js/ast/JsPrefixOperation.java
index e66e6883eb3..6c0724af93d 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsPrefixOperation.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsPrefixOperation.java
@@ -4,9 +4,6 @@
 
 package com.google.dart.compiler.backend.js.ast;
 
-/**
- * A JavaScript prefix operation.
- */
 public final class JsPrefixOperation extends JsUnaryOperation implements CanBooleanEval {
 
   public JsPrefixOperation(JsUnaryOperator op) {
@@ -35,18 +32,12 @@ public final class JsPrefixOperation extends JsUnaryOperation implements CanBool
       CanBooleanEval eval = (CanBooleanEval) getArg();
       return eval.isBooleanFalse();
     }
-    if (getOperator() == JsUnaryOperator.TYPEOF) {
-      return true;
-    }
-    return false;
+      return getOperator() == JsUnaryOperator.TYPEOF;
   }
 
   @Override
   public boolean isDefinitelyNotNull() {
-    if (getOperator() == JsUnaryOperator.TYPEOF) {
-      return true;
-    }
-    return getOperator() != JsUnaryOperator.VOID;
+      return getOperator() == JsUnaryOperator.TYPEOF || getOperator() != JsUnaryOperator.VOID;
   }
 
   @Override
@@ -55,11 +46,8 @@ public final class JsPrefixOperation extends JsUnaryOperation implements CanBool
   }
 
   @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    if (v.visit(this, context)) {
-      super.traverse(v, context);
-    }
-    v.endVisit(this, context);
+  public void accept(JsVisitor v, JsContext context) {
+    v.visit(this, context);
   }
 
   @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsProgram.java b/src/com/google/dart/compiler/backend/js/ast/JsProgram.java
index c22f4a3f542..6b71bea47a2 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsProgram.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsProgram.java
@@ -18,7 +18,7 @@ import static com.google.dart.compiler.backend.js.ast.JsNumberLiteral.JsIntLiter
  * A JavaScript program.
  */
 public final class JsProgram extends JsNodeImpl {
-    private final JsEmpty emptyStmt;
+    private final JsEmpty emptyStatement;
 
     private JsProgramFragment[] fragments;
 
@@ -29,19 +29,16 @@ public final class JsProgram extends JsNodeImpl {
     private final Map<String, JsStringLiteral> stringLiteralMap = new THashMap<String, JsStringLiteral>();
     private final JsScope topScope;
 
-    /**
-     * Constructs a JavaScript program object.
-     */
     public JsProgram(String unitId) {
         rootScope = new JsRootScope(this);
         topScope = new JsScope(rootScope, "Global", unitId);
         setFragmentCount(1);
 
-        emptyStmt = new JsEmpty();
+        emptyStatement = new JsEmpty();
     }
 
-    public JsEmpty getEmptyStmt() {
-        return emptyStmt;
+    public JsEmpty getEmptyStatement() {
+        return emptyStatement;
     }
 
     public JsBlock getFragmentBlock(int fragment) {
@@ -112,13 +109,15 @@ public final class JsProgram extends JsNodeImpl {
     }
 
     @Override
-    public void traverse(JsVisitor v, @Nullable JsContext context) {
-        if (v.visit(this, context)) {
-            for (JsProgramFragment fragment : fragments) {
-                v.accept(fragment);
-            }
+    public void accept(JsVisitor v, @Nullable JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        for (JsProgramFragment fragment : fragments) {
+            visitor.accept(fragment);
         }
-        v.endVisit(this, context);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsProgramFragment.java b/src/com/google/dart/compiler/backend/js/ast/JsProgramFragment.java
index a89da4065a6..3de7dfda2a7 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsProgramFragment.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsProgramFragment.java
@@ -8,27 +8,28 @@ package com.google.dart.compiler.backend.js.ast;
  * One independently loadable fragment of a {@link JsProgram}.
  */
 public class JsProgramFragment extends JsNodeImpl {
+    private final JsGlobalBlock globalBlock;
 
-  private final JsGlobalBlock globalBlock;
-
-  public JsProgramFragment() {
-    this.globalBlock = new JsGlobalBlock();
-  }
-
-  public JsBlock getGlobalBlock() {
-    return globalBlock;
-  }
-
-  @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    if (v.visit(this, context)) {
-      v.accept(globalBlock);
+    public JsProgramFragment() {
+        globalBlock = new JsGlobalBlock();
     }
-    v.endVisit(this, context);
-  }
 
-  @Override
-  public NodeKind getKind() {
-    return NodeKind.PROGRAM_FRAGMENT;
-  }
+    public JsBlock getGlobalBlock() {
+        return globalBlock;
+    }
+
+    @Override
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        visitor.accept(globalBlock);
+    }
+
+    @Override
+    public NodeKind getKind() {
+        return NodeKind.PROGRAM_FRAGMENT;
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsPropertyInitializer.java b/src/com/google/dart/compiler/backend/js/ast/JsPropertyInitializer.java
index d2a212c9145..e057f6e8ecf 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsPropertyInitializer.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsPropertyInitializer.java
@@ -39,12 +39,14 @@ public class JsPropertyInitializer extends JsNodeImpl {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            labelExpr = v.accept(labelExpr);
-            valueExpr = v.accept(valueExpr);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        labelExpr = visitor.accept(labelExpr);
+                    valueExpr = visitor.accept(valueExpr);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsRegExp.java b/src/com/google/dart/compiler/backend/js/ast/JsRegExp.java
index 3bcc404b892..18a7ca46b56 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsRegExp.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsRegExp.java
@@ -7,58 +7,56 @@ package com.google.dart.compiler.backend.js.ast;
 /**
  * A JavaScript regular expression.
  */
-public final class JsRegExp extends JsValueLiteral {
+public final class JsRegExp extends JsLiteral.JsValueLiteral {
+    private String flags;
+    private String pattern;
 
-  private String flags;
-  private String pattern;
+    public JsRegExp() {
+    }
 
-  public JsRegExp() {
-  }
+    public String getFlags() {
+        return flags;
+    }
 
-  public String getFlags() {
-    return flags;
-  }
+    public String getPattern() {
+        return pattern;
+    }
 
-  public String getPattern() {
-    return pattern;
-  }
+    @Override
+    public boolean isBooleanFalse() {
+        return false;
+    }
 
-  @Override
-  public boolean isBooleanFalse() {
-    return false;
-  }
+    @Override
+    public boolean isBooleanTrue() {
+        return true;
+    }
 
-  @Override
-  public boolean isBooleanTrue() {
-    return true;
-  }
+    @Override
+    public boolean isDefinitelyNotNull() {
+        return true;
+    }
 
-  @Override
-  public boolean isDefinitelyNotNull() {
-    return true;
-  }
+    @Override
+    public boolean isDefinitelyNull() {
+        return false;
+    }
 
-  @Override
-  public boolean isDefinitelyNull() {
-    return false;
-  }
+    public void setFlags(String suffix) {
+        flags = suffix;
+    }
 
-  public void setFlags(String suffix) {
-    this.flags = suffix;
-  }
+    public void setPattern(String re) {
+        pattern = re;
+    }
 
-  public void setPattern(String re) {
-    this.pattern = re;
-  }
+    @Override
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
 
-  @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    v.visit(this, context);
-    v.endVisit(this, context);
-  }
-
-  @Override
-  public NodeKind getKind() {
-    return NodeKind.REGEXP;
-  }
+    @Override
+    public NodeKind getKind() {
+        return NodeKind.REGEXP;
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsReturn.java b/src/com/google/dart/compiler/backend/js/ast/JsReturn.java
index a09421806ec..a347f8bd547 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsReturn.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsReturn.java
@@ -8,36 +8,37 @@ package com.google.dart.compiler.backend.js.ast;
  * A JavaScript return statement.
  */
 public final class JsReturn extends JsNodeImpl implements JsStatement {
+    private JsExpression expression;
 
-  private JsExpression expr;
-
-  public JsReturn() {
-  }
-
-  public JsReturn(JsExpression expr) {
-    this.expr = expr;
-  }
-
-  public JsExpression getExpr() {
-    return expr;
-  }
-
-  public void setExpr(JsExpression expr) {
-    this.expr = expr;
-  }
-
-  @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    if (v.visit(this, context)) {
-      if (expr != null) {
-        expr = v.accept(expr);
-      }
+    public JsReturn() {
+    }
+
+    public JsReturn(JsExpression expression) {
+        this.expression = expression;
+    }
+
+    public JsExpression getExpression() {
+        return expression;
+    }
+
+    public void setExpression(JsExpression expression) {
+        this.expression = expression;
     }
-    v.endVisit(this, context);
-  }
 
     @Override
-  public NodeKind getKind() {
-    return NodeKind.RETURN;
-  }
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        if (expression != null) {
+                        expression = visitor.accept(expression);
+                    }
+    }
+
+    @Override
+    public NodeKind getKind() {
+        return NodeKind.RETURN;
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsScope.java b/src/com/google/dart/compiler/backend/js/ast/JsScope.java
index 406069e6890..abe81550df7 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsScope.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsScope.java
@@ -67,8 +67,8 @@ public class JsScope {
 
     protected JsScope(@Nullable String description) {
         this.description = description;
-        this.parent = null;
-        this.scopeId = null;
+        parent = null;
+        scopeId = null;
     }
 
     /**
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsStringLiteral.java b/src/com/google/dart/compiler/backend/js/ast/JsStringLiteral.java
index 3cff1258798..d063843a626 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsStringLiteral.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsStringLiteral.java
@@ -7,7 +7,7 @@ package com.google.dart.compiler.backend.js.ast;
 /**
  * A JavaScript string literal expression.
  */
-public final class JsStringLiteral extends JsValueLiteral {
+public final class JsStringLiteral extends JsLiteral.JsValueLiteral {
 
   private final String value;
 
@@ -41,9 +41,8 @@ public final class JsStringLiteral extends JsValueLiteral {
   }
 
   @Override
-  public void traverse(JsVisitor v, JsContext context) {
+  public void accept(JsVisitor v, JsContext context) {
     v.visit(this, context);
-    v.endVisit(this, context);
   }
 
   @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsSwitch.java b/src/com/google/dart/compiler/backend/js/ast/JsSwitch.java
index 683dd195941..c4b3a3c1ae6 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsSwitch.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsSwitch.java
@@ -12,36 +12,38 @@ import java.util.List;
  */
 public class JsSwitch extends JsNodeImpl implements JsStatement {
 
-  private final List<JsSwitchMember> cases = new ArrayList<JsSwitchMember>();
-  private JsExpression expr;
+    private final List<JsSwitchMember> cases = new ArrayList<JsSwitchMember>();
+    private JsExpression expr;
 
-  public JsSwitch() {
-    super();
-  }
-
-  public List<JsSwitchMember> getCases() {
-    return cases;
-  }
-
-  public JsExpression getExpr() {
-    return expr;
-  }
-
-  public void setExpr(JsExpression expr) {
-    this.expr = expr;
-  }
-
-  @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    if (v.visit(this, context)) {
-      expr = v.accept(expr);
-      v.acceptWithInsertRemove(cases);
+    public JsSwitch() {
+        super();
     }
-    v.endVisit(this, context);
-  }
 
-  @Override
-  public NodeKind getKind() {
-    return NodeKind.SWITCH;
-  }
+    public List<JsSwitchMember> getCases() {
+        return cases;
+    }
+
+    public JsExpression getExpr() {
+        return expr;
+    }
+
+    public void setExpr(JsExpression expr) {
+        this.expr = expr;
+    }
+
+    @Override
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        expr = visitor.accept(expr);
+        visitor.acceptWithInsertRemove(cases);
+    }
+
+    @Override
+    public NodeKind getKind() {
+        return NodeKind.SWITCH;
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsSwitchMember.java b/src/com/google/dart/compiler/backend/js/ast/JsSwitchMember.java
index 08265369888..89b8ffdebba 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsSwitchMember.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsSwitchMember.java
@@ -21,4 +21,9 @@ public abstract class JsSwitchMember extends JsNodeImpl {
     public List<JsStatement> getStatements() {
         return statements;
     }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        visitor.acceptWithInsertRemove(statements);
+    }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsThrow.java b/src/com/google/dart/compiler/backend/js/ast/JsThrow.java
index 2c7867056f3..9345d31d15f 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsThrow.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsThrow.java
@@ -23,11 +23,13 @@ public class JsThrow extends JsNodeImpl implements JsStatement {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            expression = v.accept(expression);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        visitor.accept(expression);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsTry.java b/src/com/google/dart/compiler/backend/js/ast/JsTry.java
index cd0fde570f5..ebd3d1b2888 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsTry.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsTry.java
@@ -40,7 +40,7 @@ public class JsTry extends JsNodeImpl implements JsStatement {
     }
 
     public void setFinallyBlock(JsBlock block) {
-        this.finallyBlock = block;
+        finallyBlock = block;
     }
 
     public void setTryBlock(JsBlock block) {
@@ -48,15 +48,17 @@ public class JsTry extends JsNodeImpl implements JsStatement {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            tryBlock = v.accept(tryBlock);
-            v.acceptWithInsertRemove(catches);
-            if (finallyBlock != null) {
-                finallyBlock = v.accept(finallyBlock);
-            }
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        tryBlock = visitor.accept(tryBlock);
+        visitor.acceptWithInsertRemove(catches);
+        if (finallyBlock != null) {
+            finallyBlock = visitor.accept(finallyBlock);
         }
-        v.endVisit(this, context);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsUnaryOperation.java b/src/com/google/dart/compiler/backend/js/ast/JsUnaryOperation.java
index 669fe9a0a78..8f72f6f07d5 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsUnaryOperation.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsUnaryOperation.java
@@ -9,45 +9,46 @@ package com.google.dart.compiler.backend.js.ast;
  */
 public abstract class JsUnaryOperation extends JsExpressionImpl {
 
-  private JsExpression arg;
+    private JsExpression arg;
 
-  private final JsUnaryOperator op;
+    private final JsUnaryOperator op;
 
-  public JsUnaryOperation(JsUnaryOperator op) {
-    this(op, null);
-  }
-
-  public JsUnaryOperation(JsUnaryOperator op, JsExpression arg) {
-    super();
-    this.op = op;
-    this.arg = arg;
-  }
-
-  public JsExpression getArg() {
-    return arg;
-  }
-
-  public JsUnaryOperator getOperator() {
-    return op;
-  }
-
-  @Override
-  public final boolean hasSideEffects() {
-    return op.isModifying() || arg.hasSideEffects();
-  }
-
-  public void setArg(JsExpression arg) {
-    this.arg = arg;
-  }
-
-  @Override
-  public void traverse(JsVisitor v, JsContext context) {
-    if (op.isModifying()) {
-      // The delete operator is practically like an assignment of undefined, so
-      // for practical purposes we're treating it as an lvalue.
-      arg = v.acceptLvalue(arg);
-    } else {
-      arg = v.accept(arg);
+    public JsUnaryOperation(JsUnaryOperator op) {
+        this(op, null);
+    }
+
+    public JsUnaryOperation(JsUnaryOperator op, JsExpression arg) {
+        super();
+        this.op = op;
+        this.arg = arg;
+    }
+
+    public JsExpression getArg() {
+        return arg;
+    }
+
+    public JsUnaryOperator getOperator() {
+        return op;
+    }
+
+    @Override
+    public final boolean hasSideEffects() {
+        return op.isModifying() || arg.hasSideEffects();
+    }
+
+    public void setArg(JsExpression arg) {
+        this.arg = arg;
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        if (op.isModifying()) {
+            // The delete operator is practically like an assignment of undefined, so
+            // for practical purposes we're treating it as an lvalue.
+            arg = visitor.acceptLvalue(arg);
+        }
+        else {
+            arg = visitor.accept(arg);
+        }
     }
-  }
 }
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsValueLiteral.java b/src/com/google/dart/compiler/backend/js/ast/JsValueLiteral.java
deleted file mode 100644
index f64eb794ad6..00000000000
--- a/src/com/google/dart/compiler/backend/js/ast/JsValueLiteral.java
+++ /dev/null
@@ -1,23 +0,0 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-package com.google.dart.compiler.backend.js.ast;
-
-/**
- * A JavaScript string literal expression.
- */
-public abstract class JsValueLiteral extends JsLiteral {
-    protected JsValueLiteral() {
-    }
-
-    @Override
-    public final boolean hasSideEffects() {
-        return false;
-    }
-
-    @Override
-    public final boolean isLeaf() {
-        return true;
-    }
-}
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsVars.java b/src/com/google/dart/compiler/backend/js/ast/JsVars.java
index 638a50ef496..359199e77b3 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsVars.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsVars.java
@@ -81,13 +81,15 @@ public class JsVars extends JsNodeImpl implements JsStatement, Iterable<JsVars.J
         }
 
         @Override
-        public void traverse(JsVisitor v, JsContext context) {
-            if (v.visit(this, context)) {
-                if (initExpression != null) {
-                    initExpression = v.accept(initExpression);
-                }
+        public void accept(JsVisitor v, JsContext context) {
+            v.visit(this, context);
+        }
+
+        @Override
+        public void acceptChildren(JsVisitor visitor, JsContext context) {
+            if (initExpression != null) {
+                initExpression = visitor.accept(initExpression);
             }
-            v.endVisit(this, context);
         }
 
         @Override
@@ -116,11 +118,13 @@ public class JsVars extends JsNodeImpl implements JsStatement, Iterable<JsVars.J
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            v.acceptWithInsertRemove(vars);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        visitor.acceptWithInsertRemove(vars);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsVisitable.java b/src/com/google/dart/compiler/backend/js/ast/JsVisitable.java
deleted file mode 100644
index 8471d466e0e..00000000000
--- a/src/com/google/dart/compiler/backend/js/ast/JsVisitable.java
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-package com.google.dart.compiler.backend.js.ast;
-
-import com.google.dart.compiler.common.HasSourceInfo;
-
-public interface JsVisitable extends HasSourceInfo {
-  /**
-   * Causes this object to have the visitor visit itself and its children.
-   * 
-   * @param visitor the visitor that should traverse this node
-   * @param context the context of an existing traversal
-   */
-  void traverse(JsVisitor visitor, JsContext context);
-}
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsVisitor.java b/src/com/google/dart/compiler/backend/js/ast/JsVisitor.java
index dbcd5e1b9ce..ae85a3d4724 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsVisitor.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsVisitor.java
@@ -8,10 +8,7 @@ import com.google.dart.compiler.backend.js.ast.JsVars.JsVar;
 
 import java.util.List;
 
-/**
- * Implemented by nodes that will visit child nodes.
- */
-abstract public class JsVisitor {
+public abstract class JsVisitor {
     protected static final JsContext LVALUE_CONTEXT = new JsContext() {
         @Override
         public boolean canInsert() {
@@ -24,12 +21,12 @@ abstract public class JsVisitor {
         }
 
         @Override
-        public void insertAfter(JsVisitable node) {
+        public void insertAfter(JsNode node) {
             throw new UnsupportedOperationException();
         }
 
         @Override
-        public void insertBefore(JsVisitable node) {
+        public void insertBefore(JsNode node) {
             throw new UnsupportedOperationException();
         }
 
@@ -44,13 +41,12 @@ abstract public class JsVisitor {
         }
 
         @Override
-        public void replaceMe(JsVisitable node) {
+        public void replaceMe(JsNode node) {
             throw new UnsupportedOperationException();
         }
     };
 
     protected static final JsContext UNMODIFIABLE_CONTEXT = new JsContext() {
-
         @Override
         public boolean canInsert() {
             return false;
@@ -62,12 +58,12 @@ abstract public class JsVisitor {
         }
 
         @Override
-        public void insertAfter(JsVisitable node) {
+        public void insertAfter(JsNode node) {
             throw new UnsupportedOperationException();
         }
 
         @Override
-        public void insertBefore(JsVisitable node) {
+        public void insertBefore(JsNode node) {
             throw new UnsupportedOperationException();
         }
 
@@ -82,17 +78,17 @@ abstract public class JsVisitor {
         }
 
         @Override
-        public void replaceMe(JsVisitable node) {
+        public void replaceMe(JsNode node) {
             throw new UnsupportedOperationException();
         }
     };
 
-    public <T extends JsVisitable> T accept(T node) {
+    public <T extends JsNode> T accept(T node) {
         doTraverse(node, UNMODIFIABLE_CONTEXT);
         return node;
     }
 
-    public final <T extends JsVisitable> void acceptList(List<T> collection) {
+    public final <T extends JsNode> void acceptList(List<T> collection) {
         for (T node : collection) {
             doTraverse(node, UNMODIFIABLE_CONTEXT);
         }
@@ -103,138 +99,12 @@ abstract public class JsVisitor {
         return expr;
     }
 
-    public final <T extends JsVisitable> void acceptWithInsertRemove(List<T> collection) {
+    public final <T extends JsNode> void acceptWithInsertRemove(List<T> collection) {
         for (T node : collection) {
             doTraverse(node, UNMODIFIABLE_CONTEXT);
         }
     }
 
-    public void endVisit(JsArrayAccess x, JsContext ctx) {
-    }
-
-    public void endVisit(JsArrayLiteral x, JsContext ctx) {
-    }
-
-    public void endVisit(JsBinaryOperation x, JsContext ctx) {
-    }
-
-    public void endVisit(JsBlock x, JsContext ctx) {
-    }
-
-    public void endVisit(JsLiteral.JsBooleanLiteral x, JsContext ctx) {
-    }
-
-    public void endVisit(JsBreak x, JsContext ctx) {
-    }
-
-    public void endVisit(JsCase x, JsContext ctx) {
-    }
-
-    public void endVisit(JsCatch x, JsContext ctx) {
-    }
-
-    public void endVisit(JsConditional x, JsContext ctx) {
-    }
-
-    public void endVisit(JsContinue x, JsContext ctx) {
-    }
-
-    public void endVisit(JsDebugger x, JsContext ctx) {
-    }
-
-    public void endVisit(JsDefault x, JsContext ctx) {
-    }
-
-    public void endVisit(JsDoWhile x, JsContext ctx) {
-    }
-
-    public void endVisit(JsEmpty x, JsContext ctx) {
-    }
-
-    public void endVisit(JsExpressionStatement x, JsContext ctx) {
-    }
-
-    public void endVisit(JsFor x, JsContext ctx) {
-    }
-
-    public void endVisit(JsForIn x, JsContext ctx) {
-    }
-
-    public void endVisit(JsFunction x, JsContext ctx) {
-    }
-
-    public void endVisit(JsIf x, JsContext ctx) {
-    }
-
-    public void endVisit(JsInvocation x, JsContext ctx) {
-    }
-
-    public void endVisit(JsLabel x, JsContext ctx) {
-    }
-
-    public void endVisit(JsNameRef x, JsContext ctx) {
-    }
-
-    public void endVisit(JsNew x, JsContext ctx) {
-    }
-
-    public void endVisit(JsNullLiteral x, JsContext ctx) {
-    }
-
-    public void endVisit(JsNumberLiteral x, JsContext ctx) {
-    }
-
-    public void endVisit(JsObjectLiteral x, JsContext ctx) {
-    }
-
-    public void endVisit(JsParameter x, JsContext ctx) {
-    }
-
-    public void endVisit(JsPostfixOperation x, JsContext ctx) {
-    }
-
-    public void endVisit(JsPrefixOperation x, JsContext ctx) {
-    }
-
-    public void endVisit(JsProgram x, JsContext ctx) {
-    }
-
-    public void endVisit(JsProgramFragment x, JsContext ctx) {
-    }
-
-    public void endVisit(JsPropertyInitializer x, JsContext ctx) {
-    }
-
-    public void endVisit(JsRegExp x, JsContext ctx) {
-    }
-
-    public void endVisit(JsReturn x, JsContext ctx) {
-    }
-
-    public void endVisit(JsStringLiteral x, JsContext ctx) {
-    }
-
-    public void endVisit(JsSwitch x, JsContext ctx) {
-    }
-
-    public void endVisit(JsLiteral.JsThisRef x, JsContext ctx) {
-    }
-
-    public void endVisit(JsThrow x, JsContext ctx) {
-    }
-
-    public void endVisit(JsTry x, JsContext ctx) {
-    }
-
-    public void endVisit(JsVar x, JsContext ctx) {
-    }
-
-    public void endVisit(JsVars x, JsContext ctx) {
-    }
-
-    public void endVisit(JsWhile x, JsContext ctx) {
-    }
-
     public boolean visit(JsArrayAccess x, JsContext ctx) {
         return true;
     }
@@ -287,8 +157,7 @@ abstract public class JsVisitor {
         return true;
     }
 
-    public boolean visit(JsEmpty x, JsContext ctx) {
-        return true;
+    public void visit(JsEmpty x, JsContext ctx) {
     }
 
     public boolean visit(JsExpressionStatement x, JsContext ctx) {
@@ -327,16 +196,13 @@ abstract public class JsVisitor {
         return true;
     }
 
-    public boolean visit(JsNullLiteral x, JsContext ctx) {
-        return true;
+    public void visit(JsNullLiteral x, JsContext ctx) {
     }
 
-    public boolean visit(JsNumberLiteral.JsIntLiteral x, JsContext ctx) {
-        return true;
+    public void visit(JsNumberLiteral.JsIntLiteral x, JsContext ctx) {
     }
 
-    public boolean visit(JsNumberLiteral.JsDoubleLiteral x, JsContext ctx) {
-        return true;
+    public void visit(JsNumberLiteral.JsDoubleLiteral x, JsContext ctx) {
     }
 
     public boolean visit(JsObjectLiteral x, JsContext ctx) {
@@ -367,16 +233,14 @@ abstract public class JsVisitor {
         return true;
     }
 
-    public boolean visit(JsRegExp x, JsContext ctx) {
-        return true;
+    public void visit(JsRegExp x, JsContext ctx) {
     }
 
     public boolean visit(JsReturn x, JsContext ctx) {
         return true;
     }
 
-    public boolean visit(JsStringLiteral x, JsContext ctx) {
-        return true;
+    public void visit(JsStringLiteral x, JsContext ctx) {
     }
 
     public boolean visit(JsSwitch x, JsContext ctx) {
@@ -411,7 +275,7 @@ abstract public class JsVisitor {
         return true;
     }
 
-    protected void doTraverse(JsVisitable node, JsContext context) {
-        node.traverse(this, context);
+    protected void doTraverse(JsNode node, JsContext context) {
+        node.accept(this, context);
     }
-}
+}
\ No newline at end of file
diff --git a/src/com/google/dart/compiler/backend/js/ast/JsWhile.java b/src/com/google/dart/compiler/backend/js/ast/JsWhile.java
index c00d355335d..6e7d24d0d61 100644
--- a/src/com/google/dart/compiler/backend/js/ast/JsWhile.java
+++ b/src/com/google/dart/compiler/backend/js/ast/JsWhile.java
@@ -36,12 +36,14 @@ public class JsWhile extends JsNodeImpl implements JsStatement {
     }
 
     @Override
-    public void traverse(JsVisitor v, JsContext context) {
-        if (v.visit(this, context)) {
-            condition = v.accept(condition);
-            body = v.accept(body);
-        }
-        v.endVisit(this, context);
+    public void accept(JsVisitor v, JsContext context) {
+        v.visit(this, context);
+    }
+
+    @Override
+    public void acceptChildren(JsVisitor visitor, JsContext context) {
+        condition = visitor.accept(condition);
+        body = visitor.accept(body);
     }
 
     @Override
diff --git a/src/com/google/dart/compiler/backend/js/ast/RecursiveJsVisitor.java b/src/com/google/dart/compiler/backend/js/ast/RecursiveJsVisitor.java
new file mode 100644
index 00000000000..6f3b9c4f495
--- /dev/null
+++ b/src/com/google/dart/compiler/backend/js/ast/RecursiveJsVisitor.java
@@ -0,0 +1,4 @@
+package com.google.dart.compiler.backend.js.ast;
+
+public abstract class RecursiveJsVisitor extends JsVisitor {
+}