Revert "Remove JavaScriptBackend from ClosedWorldBase"

tests/compiler/dart2js/kernel/closed_world_test.dart

 // Copyright (c) 2016, 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.
 
 // Tests that the closed world computed from [WorldImpact]s derived from kernel
 // is equivalent to the original computed from resolution.
 library dart2js.kernel.closed_world_test;
 
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/closure.dart';
@@ skipping 82 matching lines @@
         entryPoint: entryPoint,
         memorySourceFiles: memorySourceFiles,
         options: [
           Flags.analyzeOnly,
           Flags.useKernel,
           Flags.enableAssertMessage
         ]);
     ElementResolutionWorldBuilder.useInstantiationMap = true;
     compiler.resolution.retainCachesForTesting = true;
     await compiler.run(entryPoint);
-    compiler.resolutionWorldBuilder.closeWorld();
+    compiler.resolutionWorldBuilder.closeWorld(compiler.reporter);
 
     JavaScriptBackend backend = compiler.backend;
     // Create a new resolution enqueuer and feed it with the [WorldImpact]s
     // computed from kernel through the [build] in `kernel_impact.dart`.
-    List list = createResolutionEnqueuerListener(compiler);
-    ResolutionEnqueuerListener resolutionEnqueuerListener = list[0];
-    BackendUsageBuilder backendUsageBuilder = list[1];
     ResolutionEnqueuer enqueuer = new ResolutionEnqueuer(
         compiler.enqueuer,
         compiler.options,
         compiler.reporter,
         const TreeShakingEnqueuerStrategy(),
-        resolutionEnqueuerListener,
+        createResolutionEnqueuerListener(compiler),
         new ElementResolutionWorldBuilder(
             backend, compiler.resolution, const OpenWorldStrategy()),
         new KernelWorkItemBuilder(compiler),
         'enqueuer from kernel');
     ClosedWorld closedWorld = computeClosedWorld(
         compiler.reporter, enqueuer, compiler.elementEnvironment);
-    BackendUsage backendUsage = backendUsageBuilder.close();
+    BackendUsage backendUsage = compiler.backend.backendUsageBuilder.close();
     checkResolutionEnqueuers(
         backendUsage, backendUsage, compiler.enqueuer.resolution, enqueuer,
         typeEquivalence: (ResolutionDartType a, ResolutionDartType b) {
       return areTypesEquivalent(unalias(a), unalias(b));
     }, elementFilter: (Element element) {
       if (element is ConstructorElement && element.isRedirectingFactory) {
         // Redirecting factory constructors are skipped in kernel.
         return false;
       }
       if (element is ClassElement) {
         for (ConstructorElement constructor in element.constructors) {
           if (!constructor.isRedirectingFactory) {
             return true;
           }
         }
         // The class cannot itself be instantiated.
         return false;
       }
       return true;
     }, verbose: arguments.verbose);
     checkClosedWorlds(
         compiler.resolutionWorldBuilder.closedWorldForTesting, closedWorld,
         verbose: arguments.verbose);
   });
 }
 
-List createResolutionEnqueuerListener(Compiler compiler) {
+EnqueuerListener createResolutionEnqueuerListener(Compiler compiler) {
   JavaScriptBackend backend = compiler.backend;
-  BackendUsageBuilder backendUsageBuilder =
-      new BackendUsageBuilderImpl(compiler.commonElements);
-  ResolutionEnqueuerListener listener = new ResolutionEnqueuerListener(
+  return new ResolutionEnqueuerListener(
       compiler.options,
       compiler.elementEnvironment,
       compiler.commonElements,
       backend.impacts,
       backend.nativeBasicData,
-      new InterceptorDataBuilderImpl(backend.nativeBasicData,
-          compiler.elementEnvironment, compiler.commonElements),
-      backendUsageBuilder,
+      backend.interceptorDataBuilder,
+      backend.backendUsageBuilder,
       backend.rtiNeedBuilder,
       backend.mirrorsDataBuilder,
       backend.noSuchMethodRegistry,
       backend.customElementsResolutionAnalysis,
       backend.lookupMapResolutionAnalysis,
       backend.mirrorsResolutionAnalysis,
-      new TypeVariableResolutionAnalysis(
-          compiler.elementEnvironment, backend.impacts, backendUsageBuilder),
+      new TypeVariableResolutionAnalysis(compiler.elementEnvironment,
+          backend.impacts, backend.backendUsageBuilder),
       backend.nativeResolutionEnqueuer,
       compiler.deferredLoadTask,
       backend.kernelTask);
-  return [listener, backendUsageBuilder];
 }
 
 ClosedWorld computeClosedWorld(DiagnosticReporter reporter,
     ResolutionEnqueuer enqueuer, ElementEnvironment elementEnvironment) {
   enqueuer.open(const ImpactStrategy(), elementEnvironment.mainFunction,
       elementEnvironment.libraries);
   enqueuer.forEach((WorkItem work) {
     enqueuer.applyImpact(work.run(), impactSource: work.element);
   });
-  return enqueuer.worldBuilder.closeWorld();
+  return enqueuer.worldBuilder.closeWorld(reporter);
 }
 
 class KernelWorkItemBuilder implements WorkItemBuilder {
   final Compiler _compiler;
 
   KernelWorkItemBuilder(this._compiler);
 
   @override
   WorkItem createWorkItem(MemberEntity entity) {
     return new KernelWorkItem(
         _compiler, _compiler.backend.impactTransformer, entity);
   }
 }
 
 class KernelWorkItem implements ResolutionWorkItem {
   final Compiler _compiler;
   final ImpactTransformer _impactTransformer;
   final MemberElement element;
 
   KernelWorkItem(this._compiler, this._impactTransformer, this.element);
 
   @override
   WorldImpact run() {
     ResolutionImpact resolutionImpact = build(_compiler, element.resolvedAst);
     return _impactTransformer.transformResolutionImpact(resolutionImpact);
   }
 }