Replace Backend with JavaScriptBackend.

pkg/compiler/lib/src/js_backend/enqueuer.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.js.enqueue;
 
 import 'dart:collection' show Queue;
 
-import '../common/backend_api.dart' show Backend;
 import '../common/codegen.dart' show CodegenWorkItem;
 import '../common/tasks.dart' show CompilerTask;
 import '../common/work.dart' show WorkItem;
 import '../common.dart';
 import '../elements/resolution_types.dart'
     show ResolutionDartType, ResolutionInterfaceType;
 import '../elements/elements.dart' show MemberElement, TypedElement;
 import '../elements/entities.dart';
 import '../enqueue.dart';
+import '../js_backend/backend.dart' show JavaScriptBackend;
 import '../native/native.dart' as native;
 import '../options.dart';
 import '../types/types.dart' show TypeMaskStrategy;
 import '../universe/world_builder.dart';
 import '../universe/use.dart'
     show DynamicUse, StaticUse, StaticUseKind, TypeUse, TypeUseKind;
 import '../universe/world_impact.dart'
     show ImpactUseCase, WorldImpact, WorldImpactVisitor;
 import '../util/enumset.dart';
 import '../util/util.dart' show Setlet;
 
 /// [Enqueuer] which is specific to code generation.
 class CodegenEnqueuer extends EnqueuerImpl {
   final String name;
   final EnqueuerStrategy strategy;
 
   Set<ClassEntity> _recentClasses = new Setlet<ClassEntity>();
   final CodegenWorldBuilderImpl _universe;
   final WorkItemBuilder _workItemBuilder;
 
   bool queueIsClosed = false;
   final CompilerTask task;
   final native.NativeEnqueuer nativeEnqueuer;
-  final Backend _backend;
+  final JavaScriptBackend _backend;
   final CompilerOptions _options;
 
   WorldImpactVisitor _impactVisitor;
 
   final Queue<WorkItem> _queue = new Queue<WorkItem>();
 
   /// All declaration elements that have been processed by codegen.
   final Set<Entity> _processedEntities = new Set<Entity>();
 
   static const ImpactUseCase IMPACT_USE =
       const ImpactUseCase('CodegenEnqueuer');
 
-  CodegenEnqueuer(
-      this.task, Backend backend, CompilerOptions options, this.strategy)
+  CodegenEnqueuer(this.task, JavaScriptBackend backend, CompilerOptions options,
+      this.strategy)
       : _universe =
             new CodegenWorldBuilderImpl(backend, const TypeMaskStrategy()),
         _workItemBuilder = new CodegenWorkItemBuilder(backend, options),
         nativeEnqueuer = backend.nativeCodegenEnqueuer(),
         this._backend = backend,
         this._options = options,
         this.name = 'codegen enqueuer' {
     _impactVisitor = new EnqueuerImplImpactVisitor(this);
   }
 
@@ skipping 184 matching lines @@
   @override
   Iterable<Entity> get processedEntities => _processedEntities;
 
   @override
   Iterable<ClassEntity> get processedClasses => _universe.processedClasses;
 }
 
 /// Builder that creates the work item necessary for the code generation of a
 /// [MemberElement].
 class CodegenWorkItemBuilder extends WorkItemBuilder {
-  Backend _backend;
+  JavaScriptBackend _backend;
   CompilerOptions _options;
 
   CodegenWorkItemBuilder(this._backend, this._options);
 
   @override
   WorkItem createWorkItem(MemberElement element) {
     assert(invariant(element, element.isDeclaration));
     // Don't generate code for foreign elements.
     if (_backend.isForeign(element)) return null;
     if (element.isAbstract) return null;
 
     // Codegen inlines field initializers. It only needs to generate
     // code for checked setters.
     if (element.isField && element.isInstanceMember) {
       if (!_options.enableTypeAssertions ||
           element.enclosingElement.isClosure) {
         return null;
       }
     }
     return new CodegenWorkItem(_backend, element);
   }
 }