Add ClosedWorld.elementEnvironment and remove Compiler.elementEnvironment

pkg/compiler/lib/src/js_model/js_strategy.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.strategy;
 
 import '../backend_strategy.dart';
 import '../common_elements.dart';
 import '../compiler.dart';
 import '../elements/elements.dart' show TypedefElement;
@@ skipping 71 matching lines @@
       });
     }
 
     closedWorld
         .getClassHierarchyNode(closedWorld.commonElements.objectClass)
         .forEachSubclass((ClassEntity cls) {
       convertClassSet(closedWorld.getClassSet(cls));
     }, ClassHierarchyNode.ALL);
 
     return new JsClosedWorld(
+        // TODO(johnniwinther): Create a JsElementEnvironment.
+        elementEnvironment: closedWorld.elementEnvironment,
         commonElements: commonElements,
         constantSystem: const JavaScriptConstantSystem(),
         backendUsage: backendUsage,
         nativeData: nativeData,
         interceptorData: interceptorData,
         classHierarchyNodes: classHierarchyNodes,
         classSets: classSets,
         implementedClasses: implementedClasses,
         // TODO(johnniwinther): Support this.
         allTypedefs: new ImmutableEmptySet<TypedefElement>());
@@ skipping 20 matching lines @@
   @override
   WorkItemBuilder createCodegenWorkItemBuilder(ClosedWorld closedWorld) {
     return new KernelCodegenWorkItemBuilder(_compiler.backend, closedWorld);
   }
 
   @override
   CodegenWorldBuilder createCodegenWorldBuilder(
       NativeBasicData nativeBasicData,
       ClosedWorld closedWorld,
       SelectorConstraintsStrategy selectorConstraintsStrategy) {
-    return new KernelCodegenWorldBuilder(_compiler.elementEnvironment,
+    return new KernelCodegenWorldBuilder(closedWorld.elementEnvironment,
         nativeBasicData, closedWorld, selectorConstraintsStrategy);
   }
 }