Remove BackendClasses and JavaScriptBackendClasses.

pkg/compiler/lib/src/js_backend/resolution_listener.dart

Index: pkg/compiler/lib/src/js_backend/resolution_listener.dart
diff --git a/pkg/compiler/lib/src/js_backend/resolution_listener.dart b/pkg/compiler/lib/src/js_backend/resolution_listener.dart
index 62708445bec35ab5822d14f99cbdf8dcb34e85a4..e1d07ae1e4c1dbc377d10835b1511244700f7142 100644
--- a/pkg/compiler/lib/src/js_backend/resolution_listener.dart
+++ b/pkg/compiler/lib/src/js_backend/resolution_listener.dart
@@ -4,7 +4,6 @@
 
 library js_backend.backend.resolution_listener;
 
-import '../common/backend_api.dart';
 import '../common/names.dart' show Identifiers, Uris;
 import '../common_elements.dart' show CommonElements, ElementEnvironment;
 import '../constants/values.dart';
@@ -41,7 +40,6 @@ class ResolutionEnqueuerListener extends EnqueuerListener {
   final ElementEnvironment _elementEnvironment;
   final CommonElements _commonElements;
   final BackendImpacts _impacts;
-  final BackendClasses _backendClasses;
 
   final NativeBasicData _nativeData;
   final InterceptorDataBuilder _interceptorData;
@@ -65,7 +63,6 @@ class ResolutionEnqueuerListener extends EnqueuerListener {
       this._elementEnvironment,
       this._commonElements,
       this._impacts,
-      this._backendClasses,
       this._nativeData,
       this._interceptorData,
       this._backendUsage,
@@ -268,7 +265,7 @@ class ResolutionEnqueuerListener extends EnqueuerListener {
           null));
       _backendUsage.registerBackendFunctionUse(helper);
       impactBuilder
-          .registerTypeUse(new TypeUse.instantiation(_backendClasses.typeType));
+          .registerTypeUse(new TypeUse.instantiation(_commonElements.typeType));
     }
   }
 
@@ -276,7 +273,7 @@ class ResolutionEnqueuerListener extends EnqueuerListener {
       DartType type, WorldImpactBuilder impactBuilder) {
     if (type is InterfaceType) {
       impactBuilder.registerTypeUse(new TypeUse.instantiation(type));
-      if (type.element == _backendClasses.typeClass) {
+      if (type.element == _commonElements.typeLiteralClass) {
         // If we use a type literal in a constant, the compile time
         // constant emitter will generate a call to the createRuntimeType
         // helper so we register a use of that.