Merge CommonElements and BackendHelpers!

pkg/compiler/lib/src/world.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.
 
 library dart2js.world;
 
 import 'closure.dart' show ClosureClassElement, SynthesizedCallMethodElementX;
 import 'common/backend_api.dart' show BackendClasses;
 import 'common.dart';
 import 'constants/constant_system.dart';
@@ skipping 699 matching lines @@
       // Vacuously true.
       return true;
     }
     return classSet.hasOnlyInstantiatedSubclasses;
   }
 
   @override
   ClassElement getLubOfInstantiatedSubclasses(ClassElement cls) {
     assert(isClosed);
     if (nativeData.isJsInteropClass(cls)) {
-      return _backend.helpers.jsJavaScriptObjectClass;
+      return commonElements.jsJavaScriptObjectClass;
     }
     ClassHierarchyNode hierarchy = _classHierarchyNodes[cls.declaration];
     return hierarchy != null
         ? hierarchy.getLubOfInstantiatedSubclasses()
         : null;
   }
 
   @override
   ClassElement getLubOfInstantiatedSubtypes(ClassElement cls) {
     assert(isClosed);
     if (nativeData.isJsInteropClass(cls)) {
-      return _backend.helpers.jsJavaScriptObjectClass;
+      return commonElements.jsJavaScriptObjectClass;
     }
     ClassSet classSet = _classSets[cls.declaration];
     return classSet != null ? classSet.getLubOfInstantiatedSubtypes() : null;
   }
 
   /// Returns an iterable over the common supertypes of the [classes].
   Iterable<ClassElement> commonSupertypesOf(Iterable<ClassElement> classes) {
     assert(isClosed);
     Iterator<ClassElement> iterator = classes.iterator;
     if (!iterator.moveNext()) return const <ClassElement>[];
@@ skipping 448 matching lines @@
       return getMightBePassedToApply(element.expression);
     }
     return functionsThatMightBePassedToApply.contains(element);
   }
 
   @override
   bool getCurrentlyKnownMightBePassedToApply(Element element) {
     return getMightBePassedToApply(element);
   }
 }