diff --git a/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsContext.java b/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsContext.java
index ae859fc93d4..7716fc1cdaa 100644
--- a/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsContext.java
+++ b/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsContext.java
@@ -11,21 +11,21 @@ import org.jetbrains.annotations.Nullable;
  * possible operations a JsVisitor subclass can perform on the currently visited
  * node.
  */
-public interface JsContext {
-  boolean canInsert();
+public abstract class JsContext<T extends JsNode> {
+  public abstract boolean canInsert();
 
-  boolean canRemove();
+  public abstract boolean canRemove();
 
-  void insertAfter(JsNode node);
+  public abstract <R extends T> void insertAfter(R node);
 
-  void insertBefore(JsNode node);
+  public abstract <R extends T> void insertBefore(R node);
 
-  boolean isLvalue();
+  public abstract boolean isLvalue();
 
-  void removeMe();
+  public abstract void removeMe();
 
-  void replaceMe(JsNode node);
+  public abstract <R extends T> void replaceMe(R node);
 
   @Nullable
-  JsNode getCurrentNode();
+  public abstract T getCurrentNode();
 }
diff --git a/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsEmpty.kt b/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsEmpty.kt
index 01a409e27a0..2233a64af81 100644
--- a/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsEmpty.kt
+++ b/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsEmpty.kt
@@ -10,7 +10,7 @@ public object JsEmpty : SourceInfoAwareJsNode(), JsStatement {
         v.visitEmpty(this)
     }
 
-    override fun traverse(v: JsVisitorWithContext, ctx: JsContext) {
+    override fun traverse(v: JsVisitorWithContext, ctx: JsContext<*>) {
         v.visit(this, ctx)
         v.endVisit(this, ctx)
     }
diff --git a/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsVisitorWithContext.java b/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsVisitorWithContext.java
index 6ff6b7d1c75..9d4224e686e 100644
--- a/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsVisitorWithContext.java
+++ b/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsVisitorWithContext.java
@@ -47,7 +47,7 @@ public abstract class JsVisitorWithContext {
         return (T) doAcceptStatement(statement);
     }
 
-    public final <T extends JsStatement> void acceptStatementList(List<T> statements) {
+    public final void acceptStatementList(List<JsStatement> statements) {
         doAcceptStatementList(statements);
     }
 
@@ -360,7 +360,7 @@ public abstract class JsVisitorWithContext {
 
     protected abstract <T extends JsStatement> JsStatement doAcceptStatement(T statement);
 
-    protected abstract <T extends JsStatement> void doAcceptStatementList(List<T> statements);
+    protected abstract void doAcceptStatementList(List<JsStatement> statements);
 
     protected abstract <T extends JsNode> void doTraverse(T node, JsContext ctx) ;
 }
diff --git a/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsVisitorWithContextImpl.java b/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsVisitorWithContextImpl.java
index 2114ac86054..839b1a679ce 100644
--- a/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsVisitorWithContextImpl.java
+++ b/js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsVisitorWithContextImpl.java
@@ -34,9 +34,9 @@ import java.util.Stack;
  */
 public class JsVisitorWithContextImpl extends JsVisitorWithContext {
 
-    private final Stack<JsContext> statementContexts = new Stack<JsContext>();
+    private final Stack<JsContext<JsStatement>> statementContexts = new Stack<JsContext<JsStatement>>();
 
-    public class ListContext<T extends JsNode> implements JsContext {
+    public class ListContext<T extends JsNode> extends JsContext<T> {
         private List<T> collection;
         private int index;
 
@@ -51,13 +51,13 @@ public class JsVisitorWithContextImpl extends JsVisitorWithContext {
         }
 
         @Override
-        public void insertAfter(JsNode node) {
+        public <R extends T> void insertAfter(R node) {
             //noinspection unchecked
             collection.add(index + 1, (T) node);
         }
 
         @Override
-        public void insertBefore(JsNode node) {
+        public <R extends T> void insertBefore(R node) {
             //noinspection unchecked
             collection.add(index++, (T) node);
         }
@@ -73,15 +73,14 @@ public class JsVisitorWithContextImpl extends JsVisitorWithContext {
         }
 
         @Override
-        public void replaceMe(JsNode node) {
+        public <R extends T> void replaceMe(R node) {
             checkReplacement(collection.get(index), node);
-            //noinspection unchecked
-            collection.set(index, (T) node);
+            collection.set(index, node);
         }
         
         @Nullable
         @Override
-        public JsNode getCurrentNode() {
+        public T getCurrentNode() {
             if (index < collection.size()) {
                 return collection.get(index);
             }
@@ -105,8 +104,7 @@ public class JsVisitorWithContextImpl extends JsVisitorWithContext {
         }
     }
 
-    @SuppressWarnings("unchecked")
-    private class NodeContext<T extends JsNode> implements JsContext {
+    private class NodeContext<T extends JsNode> extends JsContext<T> {
         protected T node;
 
         @Override
@@ -120,12 +118,12 @@ public class JsVisitorWithContextImpl extends JsVisitorWithContext {
         }
 
         @Override
-        public void insertAfter(JsNode node) {
+        public <R extends T> void insertAfter(R node) {
             throw new UnsupportedOperationException();
         }
 
         @Override
-        public void insertBefore(JsNode node) {
+        public <R extends T> void insertBefore(R node) {
             throw new UnsupportedOperationException();
         }
 
@@ -140,14 +138,14 @@ public class JsVisitorWithContextImpl extends JsVisitorWithContext {
         }
 
         @Override
-        public void replaceMe(JsNode node) {
+        public <R extends T> void replaceMe(R node) {
             checkReplacement(this.node, node);
-            this.node = (T) node;
+            this.node = node;
         }
 
         @Nullable
         @Override
-        public JsNode getCurrentNode() {
+        public T getCurrentNode() {
             return node;
         }
 
@@ -185,8 +183,8 @@ public class JsVisitorWithContextImpl extends JsVisitorWithContext {
     }
 
     @Override
-    protected <T extends JsStatement> void doAcceptStatementList(List<T> statements) {
-        ListContext<T> context = new ListContext<T>();
+    protected void doAcceptStatementList(List<JsStatement> statements) {
+        ListContext<JsStatement> context = new ListContext<JsStatement>();
         statementContexts.push(context);
         context.traverse(statements);
         statementContexts.pop();
@@ -198,7 +196,7 @@ public class JsVisitorWithContextImpl extends JsVisitorWithContext {
     }
 
     @NotNull
-    protected JsContext getLastStatementLevelContext() {
+    protected JsContext<JsStatement> getLastStatementLevelContext() {
         return statementContexts.peek();
     }
 
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/FunctionReader.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/FunctionReader.kt
index 8b69ecdb5b6..e9864b48957 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/FunctionReader.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/FunctionReader.kt
@@ -149,7 +149,7 @@ private fun JsFunction.markInlineArguments(descriptor: CallableDescriptor) {
     }
 
     val visitor = object: JsVisitorWithContextImpl() {
-        override fun endVisit(x: JsInvocation?, ctx: JsContext?) {
+        override fun endVisit(x: JsInvocation?, ctx: JsContext<*>?) {
             if (x == null || ctx == null) return
 
             val qualifier: JsExpression?
@@ -180,7 +180,7 @@ private fun replaceExternalNames(function: JsFunction, externalReplacements: Map
     if (replacements.isEmpty()) return
 
     val visitor = object: JsVisitorWithContextImpl() {
-        override fun endVisit(x: JsNameRef?, ctx: JsContext?) {
+        override fun endVisit(x: JsNameRef?, ctx: JsContext<*>?) {
             if (x == null || x.getQualifier() != null) return
 
             replacements[x.getIdent()]?.let {
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/NodeRemover.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/NodeRemover.kt
index b38ba635de1..00423810be6 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/NodeRemover.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/NodeRemover.kt
@@ -22,7 +22,7 @@ import com.google.dart.compiler.backend.js.ast.JsContext
 
 private class NodeRemover<T>(val klass: Class<T>, val predicate: (T) -> Boolean): JsVisitorWithContextImpl() {
 
-    override fun <T : JsNode?> doTraverse(node: T?, ctx: JsContext?) {
+    override fun <T : JsNode?> doTraverse(node: T?, ctx: JsContext<*>?) {
         if (node == null || ctx == null) return
 
         if (klass.isInstance(node)) {
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/removeUnusedFunctionDefinitions.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/removeUnusedFunctionDefinitions.kt
index 1a3bc618f42..3af1c75e1bf 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/removeUnusedFunctionDefinitions.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/removeUnusedFunctionDefinitions.kt
@@ -66,7 +66,7 @@ private class UnusedLocalFunctionsCollector(functions: Map<JsName, JsFunction>)
         }
     }
 
-    override fun visit(x: JsPropertyInitializer?, ctx: JsContext?): Boolean {
+    override fun visit(x: JsPropertyInitializer?, ctx: JsContext<*>?): Boolean {
         val value = x?.getValueExpr()
 
         return when (value) {
@@ -75,17 +75,17 @@ private class UnusedLocalFunctionsCollector(functions: Map<JsName, JsFunction>)
         }
     }
 
-    override fun visit(x: JsFunction?, ctx: JsContext?): Boolean {
+    override fun visit(x: JsFunction?, ctx: JsContext<*>?): Boolean {
         return !(wasProcessed(x))
     }
 
-    override fun endVisit(x: JsFunction?, ctx: JsContext?) {
+    override fun endVisit(x: JsFunction?, ctx: JsContext<*>?) {
         if (x == null) return
 
         processed.add(x)
     }
 
-    override fun endVisit(x: JsNameRef?, ctx: JsContext?) {
+    override fun endVisit(x: JsNameRef?, ctx: JsContext<*>?) {
         val name = x?.getName()
         if (isFunctionReference(x) && name != null) {
             tracker.markReachable(name)
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/removeUnusedLocalFunctionDeclarations.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/removeUnusedLocalFunctionDeclarations.kt
index 7709fd75daa..349d4d7ef19 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/removeUnusedLocalFunctionDeclarations.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/removeUnusedLocalFunctionDeclarations.kt
@@ -45,7 +45,7 @@ private class UnusedInstanceCollector : JsVisitorWithContextImpl() {
     public val removableDeclarations: List<JsStatement>
         get() = tracker.removable
 
-    override fun visit(x: JsVars.JsVar?, ctx: JsContext?): Boolean {
+    override fun visit(x: JsVars.JsVar?, ctx: JsContext<*>?): Boolean {
         if (x == null) return false
 
         if (!isLocalFunctionDeclaration(x)) return super.visit(x, ctx)
@@ -64,7 +64,7 @@ private class UnusedInstanceCollector : JsVisitorWithContextImpl() {
         return false
     }
 
-    override fun visit(x: JsNameRef?, ctx: JsContext?): Boolean {
+    override fun visit(x: JsNameRef?, ctx: JsContext<*>?): Boolean {
         val name = x?.getName()
 
         if (name != null) {
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/collectors/ReferenceNameCollector.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/collectors/ReferenceNameCollector.kt
index d7844b3a8c1..cbef182a301 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/collectors/ReferenceNameCollector.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/collectors/ReferenceNameCollector.kt
@@ -28,7 +28,7 @@ class ReferenceNameCollector : JsVisitorWithContextImpl() {
     public val references: List<JsName>
         get() = referenceSet.toList()
 
-    override fun endVisit(x: JsNameRef?, ctx: JsContext?) {
+    override fun endVisit(x: JsNameRef?, ctx: JsContext<*>?) {
         val name = x?.getName()
         if (name != null) {
             referenceSet.add(name)
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/LabelNameRefreshingVisitor.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/LabelNameRefreshingVisitor.kt
index 1fde2d21ceb..ff22732ae44 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/LabelNameRefreshingVisitor.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/LabelNameRefreshingVisitor.kt
@@ -24,9 +24,9 @@ import com.google.dart.compiler.backend.js.ast.JsContext
 import com.google.dart.compiler.backend.js.ast.JsLabel
 
 class LabelNameRefreshingVisitor(val context: NamingContext, val functionScope: JsFunctionScope) : JsVisitorWithContextImpl() {
-    override fun visit(x: JsFunction?, ctx: JsContext?): Boolean = false
+    override fun visit(x: JsFunction?, ctx: JsContext<*>?): Boolean = false
 
-    override fun visit(x: JsLabel?, ctx: JsContext?): Boolean {
+    override fun visit(x: JsLabel?, ctx: JsContext<*>?): Boolean {
         val labelName = x!!.getName()
         val freshName = functionScope.enterLabel(labelName.getIdent())
 
@@ -37,7 +37,7 @@ class LabelNameRefreshingVisitor(val context: NamingContext, val functionScope:
         return super.visit(x, ctx)
     }
 
-    override fun endVisit(x: JsLabel?, ctx: JsContext?) {
+    override fun endVisit(x: JsLabel?, ctx: JsContext<*>?) {
         super.endVisit(x, ctx)
         functionScope.exitLabel()
     }
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/NameReplacingVisitor.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/NameReplacingVisitor.kt
index 2ca8a6809e5..274f8c61bda 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/NameReplacingVisitor.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/NameReplacingVisitor.kt
@@ -27,7 +27,7 @@ import com.google.dart.compiler.backend.js.ast.JsLabel
 
 class NameReplacingVisitor(private val replaceMap: Map<JsName, JsExpression>) : JsVisitorWithContextImpl() {
 
-    override fun endVisit(x: JsNameRef?, ctx: JsContext?) {
+    override fun endVisit(x: JsNameRef?, ctx: JsContext<*>?) {
         if (x == null || ctx == null) return
 
         val replacement = replaceMap[x.getName()]
@@ -36,7 +36,7 @@ class NameReplacingVisitor(private val replaceMap: Map<JsName, JsExpression>) :
         ctx.replaceMe(replacement)
     }
 
-    override fun endVisit(x: JsVars.JsVar?, ctx: JsContext?) {
+    override fun endVisit(x: JsVars.JsVar?, ctx: JsContext<*>?) {
         if (x == null || ctx == null) return
 
         val replacement = replaceMap[x.getName()]
@@ -46,7 +46,7 @@ class NameReplacingVisitor(private val replaceMap: Map<JsName, JsExpression>) :
         }
     }
 
-    override fun endVisit(x: JsLabel?, ctx: JsContext?) {
+    override fun endVisit(x: JsLabel?, ctx: JsContext<*>?) {
         if (x == null || ctx == null) return
 
         val replacement = replaceMap[x.getName()]
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/ReturnReplacingVisitor.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/ReturnReplacingVisitor.kt
index c392140ed63..53abf072419 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/ReturnReplacingVisitor.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/ReturnReplacingVisitor.kt
@@ -33,14 +33,14 @@ class ReturnReplacingVisitor(private val resultRef: JsNameRef?, private val brea
     /**
      * Prevents replacing returns in object literal
      */
-    override fun visit(x: JsObjectLiteral?, ctx: JsContext?): Boolean = false
+    override fun visit(x: JsObjectLiteral?, ctx: JsContext<*>?): Boolean = false
 
     /**
      * Prevents replacing returns in inner function
      */
-    override fun visit(x: JsFunction?, ctx: JsContext?): Boolean = false
+    override fun visit(x: JsFunction?, ctx: JsContext<*>?): Boolean = false
 
-    override fun endVisit(x: JsReturn?, ctx: JsContext?) {
+    override fun endVisit(x: JsReturn?, ctx: JsContext<*>?) {
         if (x == null || ctx == null) return
 
         if (breakLabel != null) {
diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/ThisReplacingVisitor.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/ThisReplacingVisitor.kt
index 33ff54524ad..a3dfda47f89 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/ThisReplacingVisitor.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/rewriters/ThisReplacingVisitor.kt
@@ -24,11 +24,11 @@ import com.google.dart.compiler.backend.js.ast.JsObjectLiteral
 import com.google.dart.compiler.backend.js.ast.JsVisitorWithContextImpl
 
 class ThisReplacingVisitor(private val thisReplacement: JsExpression) : JsVisitorWithContextImpl() {
-    override fun endVisit(x: JsLiteral.JsThisRef?, ctx: JsContext?) {
+    override fun endVisit(x: JsLiteral.JsThisRef?, ctx: JsContext<*>?) {
         ctx?.replaceMe(thisReplacement)
     }
 
-    override fun visit(x: JsFunction?, ctx: JsContext?) = false
+    override fun visit(x: JsFunction?, ctx: JsContext<*>?) = false
 
-    override fun visit(x: JsObjectLiteral?, ctx: JsContext?) = false
+    override fun visit(x: JsObjectLiteral?, ctx: JsContext<*>?) = false
 }