Merge CommonElements and BackendHelpers!

pkg/compiler/lib/src/js_emitter/full_emitter/class_emitter.dart

 // Copyright (c) 2013, 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_emitter.full_emitter.class_emitter;
 
 import '../../common.dart';
 import '../../common/names.dart' show Names;
 import '../../elements/resolution_types.dart' show ResolutionDartType;
 import '../../deferred_load.dart' show OutputUnit;
@@ skipping 48 matching lines @@
     if (cls.hasRtiField) {
       builder.addField(namer.rtiFieldJsName);
     }
     emitCheckedClassSetters(cls, builder);
     emitClassGettersSettersForCSP(cls, builder);
     emitInstanceMembers(cls, builder);
     emitStubs(cls.callStubs, builder);
     emitRuntimeTypeInformation(cls, builder);
     emitNativeInfo(cls, builder);
 
-    if (classElement == backend.helpers.closureClass) {
+    if (classElement == backend.commonElements.closureClass) {
       // We add a special getter here to allow for tearing off a closure from
       // itself.
       jsAst.Fun function = js('function() { return this; }');
       jsAst.Name name = namer.getterForMember(Names.call);
       builder.addProperty(name, function);
     }
 
     emitClassBuilderWithReflectionData(
         cls, builder, enclosingBuilder, fragment);
   }
@@ skipping 361 matching lines @@
     String reflectionName = emitter.getReflectionName(selector, name);
     if (reflectionName != null) {
       var reflectable = js(
           backend.mirrorsData.isMemberAccessibleByReflection(member)
               ? '1'
               : '0');
       builder.addPropertyByName('+$reflectionName', reflectable);
     }
   }
 }