Add ClosedWorld.elementEnvironment and remove Compiler.elementEnvironment

pkg/compiler/lib/src/kernel/kernel_backend_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.kernel.backend_strategy;
 
 import 'package:kernel/ast.dart' as ir;
 
 import '../backend_strategy.dart';
 import '../closure.dart';
@@ skipping 56 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);
   }
 
   @override
   SsaBuilderTask createSsaBuilderTask(JavaScriptBackend backend,
       SourceInformationStrategy sourceInformationStrategy) {
     return new KernelSsaBuilderTask(backend.compiler);
   }
 
   @override
@@ skipping 268 matching lines @@
   Iterable<ClassEntity> sortClasses(Iterable<ClassEntity> classes) {
     return classes.toList()
       ..sort((ClassEntity a, ClassEntity b) {
         int r = _compareLibraries(a.library, b.library);
         if (r != 0) return r;
         return _compareNodes(
             a, elementMap.getClassNode(a), b, elementMap.getClassNode(b));
       });
   }
 }