Support serialization of all resolved asts from dart:core

pkg/compiler/lib/src/js_backend/backend_impact.dart

 // Copyright (c) 2015, 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.
 
 library dart2js.js_helpers.impact;
 
 import '../compiler.dart' show Compiler;
 import '../core_types.dart' show CoreClasses;
 import '../dart_types.dart' show InterfaceType;
 import '../elements/elements.dart' show ClassElement, Element;
@@ skipping 273 matching lines @@
         find(JavaScriptMapConstant.DART_GENERAL_CLASS)
       ]);
     }
     return _constantMapLiteral;
   }
 
   BackendImpact _symbolConstructor;
 
   BackendImpact get symbolConstructor {
     if (_symbolConstructor == null) {
-      _symbolConstructor = new BackendImpact(
-          staticUses: [helpers.compiler.symbolValidatedConstructor]);
+      _symbolConstructor =
+          new BackendImpact(staticUses: [helpers.symbolValidatedConstructor]);
     }
     return _symbolConstructor;
   }
 
   BackendImpact _constSymbol;
 
   BackendImpact get constSymbol {
     if (_constSymbol == null) {
       _constSymbol = new BackendImpact(
           instantiatedClasses: [coreClasses.symbolClass],
@@ skipping 293 matching lines @@
   BackendImpact _closure;
 
   BackendImpact get closure {
     if (_closure == null) {
       _closure =
           new BackendImpact(instantiatedClasses: [coreClasses.functionClass]);
     }
     return _closure;
   }
 }