Replace Backend with JavaScriptBackend.

pkg/compiler/lib/src/enqueue.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.enqueue;
 
 import 'dart:collection' show Queue;
 
-import 'common/backend_api.dart' show Backend;
 import 'common/resolution.dart' show Resolution;
 import 'common/tasks.dart' show CompilerTask;
 import 'common/work.dart' show WorkItem;
 import 'common.dart';
 import 'compiler.dart' show Compiler, GlobalDependencyRegistry;
 import 'options.dart';
 import 'elements/elements.dart'
     show
         AnalyzableElement,
         ClassElement,
         ConstructorElement,
         Element,
         MemberElement;
 import 'elements/entities.dart';
 import 'elements/resolution_types.dart'
     show ResolutionDartType, ResolutionInterfaceType;
+import 'js_backend/backend.dart' show JavaScriptBackend;
 import 'native/native.dart' as native;
 import 'universe/world_builder.dart';
 import 'universe/use.dart'
     show DynamicUse, StaticUse, StaticUseKind, TypeUse, TypeUseKind;
 import 'universe/world_impact.dart'
     show ImpactStrategy, ImpactUseCase, WorldImpact, WorldImpactVisitor;
 import 'util/enumset.dart';
 import 'util/util.dart' show Setlet;
 
 class EnqueueTask extends CompilerTask {
@@ skipping 75 matching lines @@
 
 /// [Enqueuer] which is specific to resolution.
 class ResolutionEnqueuer extends EnqueuerImpl {
   static const ImpactUseCase IMPACT_USE =
       const ImpactUseCase('ResolutionEnqueuer');
 
   final CompilerTask task;
   final String name;
   final Resolution _resolution;
   final CompilerOptions _options;
-  final Backend backend;
+  final JavaScriptBackend backend;
   final GlobalDependencyRegistry _globalDependencies;
   final native.NativeEnqueuer nativeEnqueuer;
 
   final EnqueuerStrategy strategy;
   final Set<ClassEntity> _recentClasses = new Setlet<ClassEntity>();
   final ResolutionWorldBuilderImpl _universe;
   final WorkItemBuilder _workItemBuilder;
 
   bool queueIsClosed = false;
 
   WorldImpactVisitor _impactVisitor;
 
   /// All declaration elements that have been processed by the resolver.
   final Set<Entity> _processedEntities = new Set<Entity>();
 
   final Queue<WorkItem> _queue = new Queue<WorkItem>();
 
   /// Queue of deferred resolution actions to execute when the resolution queue
   /// has been emptied.
   final Queue<_DeferredAction> _deferredQueue = new Queue<_DeferredAction>();
 
   ResolutionEnqueuer(this.task, this._options, Resolution resolution,
-      this.strategy, this._globalDependencies, Backend backend,
+      this.strategy, this._globalDependencies, JavaScriptBackend backend,
       [this.name = 'resolution enqueuer'])
       : this.backend = backend,
         this._resolution = resolution,
         this.nativeEnqueuer = backend.nativeResolutionEnqueuer(),
         _universe = new ResolutionWorldBuilderImpl(
             backend, resolution, const OpenWorldStrategy()),
         _workItemBuilder = new ResolutionWorkItemBuilder(resolution) {
     _impactVisitor = new EnqueuerImplImpactVisitor(this);
   }
 
@@ skipping 364 matching lines @@
   @override
   WorkItem createWorkItem(MemberElement element) {
     assert(invariant(element, element.isDeclaration));
     if (element.isMalformed) return null;
 
     assert(invariant(element, element is AnalyzableElement,
         message: 'Element $element is not analyzable.'));
     return _resolution.createWorkItem(element);
   }
 }