Refactor ConstantSystem

tests/compiler/dart2js/mock_libraries.dart

 // Copyright (c) 2014, 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 for creating mock versions of platform and internal libraries.
 
 library mock_libraries;
 
 const DEFAULT_PLATFORM_CONFIG = """
 [libraries]
@@ skipping 80 matching lines @@
       class Object {
         const Object();
         operator ==(other) { return true; }
         get hashCode => throw "Object.hashCode not implemented.";
         String toString() { return null; }
         noSuchMethod(im) { throw im; }
       }''',
   'Resource': 'class Resource {}',
   'StackTrace': 'abstract class StackTrace {}',
   'String': 'class String implements Pattern {}',
-  'Symbol': 'class Symbol { final name; const Symbol(this.name); }',
+  'Symbol': 'class Symbol { final _name; const Symbol(this._name); }',
   'Type': 'class Type {}',
   'Pattern': 'abstract class Pattern {}',
   '_genericNoSuchMethod': '_genericNoSuchMethod(a,b,c,d,e) {}',
   '_unresolvedConstructorError': '_unresolvedConstructorError(a,b,c,d,e) {}',
   '_malformedTypeError': '_malformedTypeError(message) {}',
 };
 
 const String DEFAULT_PATCH_CORE_SOURCE = r'''
 import 'dart:_js_helper';
 import 'dart:_interceptors';
@@ skipping 347 matching lines @@
 
     const LookupMap(this._entries, [this._nestedMaps = const []])
         : _key = null, _value = null;
 
     const LookupMap.pair(this._key, this._value)
         : _entries = const [], _nestedMaps = const [];
     V operator[](K k) => null;
   }''',
   '_version': 'const _version = "0.0.1+1";',
 };