Correctly handle constness for list and map literals inside bodies.

lib/compiler/implementation/tree/nodes.dart

 // Copyright (c) 2012, 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.
 
 interface Visitor<R> {
   R visitBlock(Block node);
   R visitBreakStatement(BreakStatement node);
   R visitCatchBlock(CatchBlock node);
   R visitClassNode(ClassNode node);
   R visitConditional(Conditional node);
@@ skipping 1202 matching lines @@
 
   Token getBeginToken() => semicolonToken;
 
   Token getEndToken() => semicolonToken;
 }
 
 class LiteralMap extends Expression {
   final NodeList typeArguments;
   final NodeList entries;
 
-  LiteralMap(this.typeArguments, this.entries);
+  final Token constKeyword;
 
-  bool isConst() => false; // TODO(ahe): Store constness.
+  LiteralMap(this.typeArguments, this.entries, this.constKeyword);
+
+  bool isConst() => constKeyword !== null;
 
   LiteralMap asLiteralMap() => this;
 
   accept(Visitor visitor) => visitor.visitLiteralMap(this);
 
   visitChildren(Visitor visitor) {
     if (typeArguments != null) typeArguments.accept(visitor);
     entries.accept(visitor);
   }
 
-  Token getBeginToken() => firstBeginToken(typeArguments, entries);
+  Token getBeginToken() {
+    if (constKeyword !== null) return constKeyword;
+    return firstBeginToken(typeArguments, entries);
+  }
 
   Token getEndToken() => entries.getEndToken();
 }
 
 class LiteralMapEntry extends Node {
   final Expression key;
   final Expression value;
 
   final Token colonToken;
 
@@ skipping 388 matching lines @@
  * argument).
  *
  * TODO(ahe): This method is controversial, the team needs to discuss
  * if top-level methods are acceptable and what naming conventions to
  * use.
  */
 initializerDo(Node node, f(Node node)) {
   SendSet send = node.asSendSet();
   if (send !== null) return f(send.arguments.head);
 }