Merge CommonElements and BackendHelpers!

pkg/compiler/lib/src/js_backend/impact_transformer.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.
 
 library js_backend.backend.impact_transformer;
 
 import '../common.dart';
 import '../common_elements.dart';
 import '../common/backend_api.dart' show ImpactTransformer;
 import '../common/codegen.dart' show CodegenImpact;
 import '../common/resolution.dart' show ResolutionImpact;
 import '../constants/expressions.dart';
 import '../common_elements.dart' show ElementEnvironment;
 import '../elements/elements.dart' show AsyncMarker;
 import '../elements/entities.dart';
 import '../elements/resolution_types.dart' show Types;
 import '../elements/types.dart';
 import '../native/enqueue.dart';
 import '../native/native.dart' as native;
 import '../options.dart';
 import '../universe/feature.dart';
 import '../universe/use.dart'
     show StaticUse, StaticUseKind, TypeUse, TypeUseKind;
 import '../universe/world_impact.dart' show TransformedWorldImpact, WorldImpact;
 import '../util/util.dart';
 import 'backend.dart';
-import 'backend_helpers.dart';
 import 'backend_impact.dart';
 import 'backend_usage.dart';
 import 'checked_mode_helpers.dart';
 import 'custom_elements_analysis.dart';
 import 'interceptor_data.dart';
 import 'lookup_map_analysis.dart';
 import 'mirrors_data.dart';
 import 'namer.dart';
 import 'native_data.dart';
 
@@ skipping 290 matching lines @@
     }
     if (type is InterfaceType && _nativeBasicData.isNativeClass(type.element)) {
       registerImpact(_impacts.nativeTypeCheck);
     }
   }
 }
 
 class CodegenImpactTransformer {
   final CompilerOptions _options;
   final ElementEnvironment _elementEnvironment;
-  final BackendHelpers _helpers;
+  final CommonElements _commonElements;
   final BackendImpacts _impacts;
   final CheckedModeHelpers _checkedModeHelpers;
   final NativeData _nativeData;
   final BackendUsage _backendUsage;
   final RuntimeTypesNeed _rtiNeed;
   final NativeCodegenEnqueuer _nativeCodegenEnqueuer;
   final Namer _namer;
   final OneShotInterceptorData _oneShotInterceptorData;
   final LookupMapAnalysis _lookupMapAnalysis;
   final RuntimeTypesChecksBuilder _rtiChecksBuilder;
 
   CodegenImpactTransformer(
       this._options,
       this._elementEnvironment,
-      this._helpers,
+      this._commonElements,
       this._impacts,
       this._checkedModeHelpers,
       this._nativeData,
       this._backendUsage,
       this._rtiNeed,
       this._nativeCodegenEnqueuer,
       this._namer,
       this._oneShotInterceptorData,
       this._lookupMapAnalysis,
       this._rtiChecksBuilder);
 
   void onIsCheckForCodegen(DartType type, TransformedWorldImpact transformed) {
     if (type.isDynamic) return;
     type = type.unaliased;
     _impacts.typeCheck.registerImpact(transformed, _elementEnvironment);
 
     bool inCheckedMode = _options.enableTypeAssertions;
     // [registerIsCheck] is also called for checked mode checks, so we
     // need to register checked mode helpers.
     if (inCheckedMode) {
       // All helpers are added to resolution queue in enqueueHelpers. These
       // calls to [enqueue] with the resolution enqueuer serve as assertions
       // that the helper was in fact added.
       // TODO(13155): Find a way to enqueue helpers lazily.
       CheckedModeHelper helper =
           _checkedModeHelpers.getCheckedModeHelper(type, typeCast: false);
       if (helper != null) {
-        StaticUse staticUse = helper.getStaticUse(_helpers);
+        StaticUse staticUse = helper.getStaticUse(_commonElements);
         transformed.registerStaticUse(staticUse);
       }
       // We also need the native variant of the check (for DOM types).
       helper =
           _checkedModeHelpers.getNativeCheckedModeHelper(type, typeCast: false);
       if (helper != null) {
-        StaticUse staticUse = helper.getStaticUse(_helpers);
+        StaticUse staticUse = helper.getStaticUse(_commonElements);
         transformed.registerStaticUse(staticUse);
       }
     }
     if (!type.treatAsRaw || type.containsTypeVariables) {
       _impacts.genericIsCheck.registerImpact(transformed, _elementEnvironment);
     }
     if (type is InterfaceType && _nativeData.isNativeClass(type.element)) {
       // We will neeed to add the "$is" and "$as" properties on the
       // JavaScript object prototype, so we make sure
       // [:defineProperty:] is compiled.
@@ skipping 68 matching lines @@
           _impacts.asyncStarBody
               .registerImpact(transformed, _elementEnvironment);
           break;
       }
     }
 
     // TODO(johnniwinther): Remove eager registration.
     return transformed;
   }
 }