Add a "Label" Node around an Identifier that is being used as a label.

lib/compiler/implementation/typechecker.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.
 
 class TypeCheckerTask extends CompilerTask {
   TypeCheckerTask(Compiler compiler) : super(compiler);
   String get name() => "Type checker";
 
   static final bool LOG_FAILURES = false;
 
@@ skipping 685 matching lines @@
   visitContinueStatement(ContinueStatement node) {
     return StatementType.NOT_RETURNING;
   }
 
   visitForIn(ForIn node) {
     analyze(node.expression);
     StatementType bodyType = analyze(node.body);
     return bodyType.join(StatementType.NOT_RETURNING);
   }
 
+  visitLabel(Label node) { }
+
   visitLabeledStatement(LabeledStatement node) {
     return node.statement.accept(this);
   }
 
   visitLiteralMap(LiteralMap node) {
     fail(node);
   }
 
   visitLiteralMapEntry(LiteralMapEntry node) {
     fail(node);
@@ skipping 20 matching lines @@
   }
 
   visitCatchBlock(CatchBlock node) {
     fail(node);
   }
 
   visitTypedef(Typedef node) {
     fail(node);
   }
 }