[JS] Make sourcemaps more precise wrt JS syntax

- Generate mappings for function parameters
- Don't generate debug info for dots in qualified references
- A location of a JsNameRef is considered the start of the rightmost
  name

js/js.ast/src/org/jetbrains/kotlin/js/backend/JsToStringGenerationVisitor.java

@@ -673,10 +673,12 @@ public class JsToStringGenerationVisitor extends JsVisitor {
         pushSourceInfo(x.getSource());
         leftParen();
         boolean notFirst = false;
+        sourceLocationConsumer.pushSourceInfo(null);
         for (JsParameter param : x.getParameters()) {
             notFirst = sepCommaOptSpace(notFirst);
             accept(param);
         }
+        sourceLocationConsumer.popSourceInfo();
         rightParen();
         space();
 
@@ -845,8 +847,9 @@ public class JsToStringGenerationVisitor extends JsVisitor {
     }
 
     public void visitNameRef(@NotNull JsNameRef nameRef, boolean withQualifier) {
-        pushSourceInfo(nameRef.getSource());
+
         printCommentsBeforeNode(nameRef);
+        p.maybeIndent();
 
         JsExpression qualifier = nameRef.getQualifier();
         if (qualifier != null && withQualifier) {
@@ -869,11 +872,11 @@ public class JsToStringGenerationVisitor extends JsVisitor {
             p.print('.');
         }
 
-        p.maybeIndent();
+        pushSourceInfo(nameRef.getSource());
         p.print(nameRef.getIdent());
+        popSourceInfo();
 
         printCommentsAfterNode(nameRef);
-        popSourceInfo();
     }
 
     @Override
@@ -1004,7 +1007,9 @@ public class JsToStringGenerationVisitor extends JsVisitor {
 
     @Override
     public void visitParameter(@NotNull JsParameter x) {
+        pushSourceInfo(x.getSource());
         nameOf(x);
+        popSourceInfo();
     }
 
     @Override

js/js.parser/src/com/google/gwt/dev/js/JsAstMapper.java

@@ -589,7 +589,7 @@ public class JsAstMapper {
         while (fromParamNode != null) {
             String fromParamName = fromParamNode.getString();
             JsName name = scopeContext.localNameFor(fromParamName);
-            toFn.getParameters().add(new JsParameter(name));
+            toFn.getParameters().add(withLocation(new JsParameter(name), fromParamNode));
             fromParamNode = fromParamNode.getNext();
         }
 
@@ -1132,17 +1132,28 @@ public class JsAstMapper {
         if (astNode == null) return null;
 
         CodePosition location = node.getPosition();
-        // For functions, consider their location to be at the opening parenthesis.
-        if (node.getType() == TokenStream.FUNCTION) {
-            Node c = node.getFirstChild();
-            while (c != null && c.getType() != TokenStream.LP)
-                c = c.getNext();
-            if (c != null && c.getPosition() != null)
-                location = c.getPosition();
+        switch (node.getType()) {
+            case TokenStream.FUNCTION:
+                // For functions, consider their location to be at the opening parenthesis.
+                Node c = node.getFirstChild();
+                while (c != null && c.getType() != TokenStream.LP)
+                    c = c.getNext();
+                if (c != null && c.getPosition() != null)
+                    location = c.getPosition();
+                break;
+            case TokenStream.GETPROP:
+                // For dot-qualified references, consider their position to be at the rightmost name reference.
+                location = node.getLastChild().getPosition();
+                break;
         }
 
         if (location != null) {
-            JsLocation jsLocation = new JsLocation(fileName, location.getLine(), location.getOffset());
+            String originalName = null;
+            if (astNode instanceof JsFunction || astNode instanceof JsVars.JsVar || astNode instanceof JsParameter) {
+                JsName name = ((HasName) astNode).getName();
+                originalName = name != null ? name.toString() : null;
+            }
+            JsLocation jsLocation = new JsLocation(fileName, location.getLine(), location.getOffset(), originalName);
             if (astNode instanceof SourceInfoAwareJsNode) {
                 astNode.setSource(jsLocation);
             }

js/js.parser/src/com/google/gwt/dev/js/rhino/Node.java

@@ -203,6 +203,10 @@ public class Node implements Cloneable {
         return first;
     }
 
+    public Node getLastChild() {
+        return last;
+    }
+
     public Node getNext() {
         return next;
     }

js/js.parser/src/com/google/gwt/dev/js/rhino/Parser.java

@@ -228,10 +228,9 @@ public class Parser {
 
             if (!ts.matchToken(TokenStream.GWT)) {
                 do {
-                    CodePosition namePosition = ts.tokenPosition;
                     mustMatchToken(ts, TokenStream.NAME, "msg.no.parm");
                     String s = ts.getString();
-                    args.addChildToBack(nf.createName(s, namePosition));
+                    args.addChildToBack(nf.createName(s, ts.tokenPosition));
                 }
                 while (ts.matchToken(TokenStream.COMMA));
 

js/js.parser/src/org/jetbrains/kotlin/js/parser/sourcemaps/SourceMapLocationRemapper.kt

@@ -106,9 +106,9 @@ class SourceMapLocationRemapper(private val sourceMap: SourceMap, private val so
                 handleNode(invocation, invocation.qualifier, *invocation.arguments.toTypedArray())
 
         override fun visitFunction(x: JsFunction) {
+            nodeList += x
             x.parameters.forEach { accept(it) }
             x.body.statements.forEach { accept(it) }
-            nodeList += x
         }
 
         override fun visitElement(node: JsNode) {