Remove BackendClasses and JavaScriptBackendClasses.

tests/compiler/dart2js/kernel/closed_world2_test.dart

 // Copyright (c) 2017, 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.
 
 // Partial test that the closed world computed from [WorldImpact]s derived from
 // kernel is equivalent to the original computed from resolution.
 library dart2js.kernel.closed_world2_test;
 
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/closure.dart';
@@ skipping 96 matching lines @@
   BackendImpacts impacts = new BackendImpacts(options, commonElements);
 
   // TODO(johnniwinther): Create Kernel based implementations for these:
   NativeBasicData nativeBasicData = new NativeBasicDataImpl();
   RuntimeTypesNeedBuilder rtiNeedBuilder = new RuntimeTypesNeedBuilderImpl();
   MirrorsDataBuilder mirrorsDataBuilder = new MirrorsDataBuilderImpl();
   CustomElementsResolutionAnalysis customElementsResolutionAnalysis =
       new CustomElementsResolutionAnalysisImpl();
   MirrorsResolutionAnalysis mirrorsResolutionAnalysis =
       new MirrorsResolutionAnalysisImpl();
-
   LookupMapResolutionAnalysis lookupMapResolutionAnalysis =
       new LookupMapResolutionAnalysis(reporter, elementEnvironment);
-  BackendClasses backendClasses = new JavaScriptBackendClasses(
-      elementEnvironment, commonElements, nativeBasicData);
   InterceptorDataBuilder interceptorDataBuilder =
       new InterceptorDataBuilderImpl(
           nativeBasicData, elementEnvironment, commonElements);
   BackendUsageBuilder backendUsageBuilder =
       new BackendUsageBuilderImpl(commonElements);
   NoSuchMethodRegistry noSuchMethodRegistry = new NoSuchMethodRegistry(
       commonElements, new KernelNoSuchMethodResolver(worldBuilder));
   NativeResolutionEnqueuer nativeResolutionEnqueuer =
-      new NativeResolutionEnqueuer(
-          options,
-          elementEnvironment,
-          commonElements,
-          backendClasses,
-          backendUsageBuilder,
-          new KernelNativeClassResolver(worldBuilder));
+      new NativeResolutionEnqueuer(options, elementEnvironment, commonElements,
+          backendUsageBuilder, new KernelNativeClassResolver(worldBuilder));
 
   ResolutionEnqueuerListener listener = new ResolutionEnqueuerListener(
       options,
       elementEnvironment,
       commonElements,
       impacts,
-      backendClasses,
       nativeBasicData,
       interceptorDataBuilder,
       backendUsageBuilder,
       rtiNeedBuilder,
       mirrorsDataBuilder,
       noSuchMethodRegistry,
       customElementsResolutionAnalysis,
       lookupMapResolutionAnalysis,
       mirrorsResolutionAnalysis,
       new TypeVariableResolutionAnalysis(
@@ skipping 146 matching lines @@
   final MemberEntity element;
 
   KernelWorkItem(this._worldBuilder, this._impactTransformer, this.element);
 
   @override
   WorldImpact run() {
     ResolutionImpact impact = _worldBuilder.computeWorldImpact(element);
     return _impactTransformer.transformResolutionImpact(impact);
   }
 }