Less inequivalence on Hello World!

pkg/compiler/lib/src/js_model/elements.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 dart2js.js_model.elements;
 
 import '../common_elements.dart';
 import '../constants/constant_system.dart';
 import '../constants/values.dart';
 import '../elements/elements.dart';
@@ skipping 447 matching lines @@
   final int index;
 
   JTypeVariable(this.typeDeclaration, this.name, this.index);
 
   String toString() => 'type_variable(${typeDeclaration.name}.$name)';
 }
 
 class JsClosedWorld extends ClosedWorldBase {
   JsClosedWorld(
       {ElementEnvironment elementEnvironment,
+      DartTypes dartTypes,
       CommonElements commonElements,
       ConstantSystem constantSystem,
       NativeData nativeData,
       InterceptorData interceptorData,
       BackendUsage backendUsage,
       ResolutionWorldBuilder resolutionWorldBuilder,
       Set<ClassEntity> implementedClasses,
       FunctionSet functionSet,
       Set<TypedefElement> allTypedefs,
       Map<ClassEntity, Set<ClassEntity>> mixinUses,
       Map<ClassEntity, Set<ClassEntity>> typesImplementedBySubclasses,
       Map<ClassEntity, ClassHierarchyNode> classHierarchyNodes,
       Map<ClassEntity, ClassSet> classSets})
       : super(
             elementEnvironment: elementEnvironment,
+            dartTypes: dartTypes,
             commonElements: commonElements,
             constantSystem: constantSystem,
             nativeData: nativeData,
             interceptorData: interceptorData,
             backendUsage: backendUsage,
             resolutionWorldBuilder: resolutionWorldBuilder,
             implementedClasses: implementedClasses,
             functionSet: functionSet,
             allTypedefs: allTypedefs,
             mixinUses: mixinUses,
@@ skipping 1363 matching lines @@
   @override
   ClassEntity get numClass => _map.toBackendClass(_commonElements.numClass);
 
   @override
   ClassEntity get boolClass => _map.toBackendClass(_commonElements.boolClass);
 
   @override
   FunctionEntity get throwUnsupportedError =>
       _map.toBackendMember(_commonElements.throwUnsupportedError);
 }