Support symbol literals.

sdk/lib/_internal/compiler/implementation/compiler.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.
 
 part of dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 351 matching lines @@
   ClassElement doubleClass;
   ClassElement stringClass;
   ClassElement functionClass;
   ClassElement nullClass;
   ClassElement listClass;
   ClassElement typeClass;
   ClassElement mapClass;
   ClassElement symbolClass;
   ClassElement stackTraceClass;
 
-  // Initialized after mirrorSystemClass has been resolved.
+  // Initialized after symbolClass has been resolved.
   FunctionElement symbolConstructor;
 
   // Initialized when dart:mirrors is loaded.
   ClassElement mirrorSystemClass;
 
   // Initialized when dart:mirrors is loaded.
   ClassElement mirrorsUsedClass;
 
   // Initialized after mirrorSystemClass has been resolved.
   FunctionElement mirrorSystemGetNameFunction;
@@ skipping 1103 matching lines @@
 
   void close() {}
 
   toString() => name;
 
   /// Convenience method for getting an [api.CompilerOutputProvider].
   static NullSink outputProvider(String name, String extension) {
     return new NullSink('$name.$extension');
   }
 }