Introduce JsStrategy skeleton

pkg/compiler/lib/src/universe/element_world_builder.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.
 
 part of world_builder;
 
 /// [ResolutionEnqueuerWorldBuilder] based on the [Element] model.
 class ElementResolutionWorldBuilder extends ResolutionWorldBuilderBase {
   /// Used for testing the new more precise computation of instantiated types
   /// and classes.
@@ skipping 161 matching lines @@
     Map<ClassEntity, Set<ClassEntity>> typesImplementedBySubclasses =
         populateHierarchyNodes();
     _closed = true;
     return _closedWorldCache = new ClosedWorldImpl(
         commonElements: _commonElements,
         constantSystem: _constantSystem,
         nativeData: _nativeDataBuilder.close(),
         interceptorData: _interceptorDataBuilder.close(),
         backendUsage: _backendUsageBuilder.close(),
         resolutionWorldBuilder: this,
+        implementedClasses: _implementedClasses,
         functionSet: _allFunctions.close(),
         allTypedefs: _allTypedefs,
         mixinUses: _mixinUses,
         typesImplementedBySubclasses: typesImplementedBySubclasses,
         classHierarchyNodes: _classHierarchyNodes,
         classSets: _classSets);
   }
 
   @override
   void registerMixinUse(
       MixinApplicationElement mixinApplication, ClassElement mixin) {
     assert(mixin.isDeclaration);
     super.registerMixinUse(mixinApplication, mixin);
   }
 }