Starting making dart2js strong mode clean.

pkg/compiler/lib/src/closure.dart

 // Copyright (c) 2012, 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 closureToClassMapper;
 
 import 'common/names.dart' show Identifiers;
 import 'common/resolution.dart' show ParsingContext, Resolution;
 import 'common/tasks.dart' show CompilerTask;
 import 'common.dart';
@@ skipping 124 matching lines @@
       ClosureClassMap closureClassMap = _closureMappingCache[element];
       assert(closureClassMap != null,
           failedAt(element, "No ClosureClassMap computed for ${element}."));
       return closureClassMap;
     });
   }
 
   /// Create [ClosureClassMap]s for all live members.
   void createClosureClasses(ClosedWorldRefiner closedWorldRefiner) {
     compiler.enqueuer.resolution.processedEntities
-        .forEach((MemberElement element) {
+        .forEach((MemberEntity _element) {
+      MemberElement element = _element;
       ResolvedAst resolvedAst = element.resolvedAst;
       if (element.isAbstract) return;
       if (element.isField &&
           !element.isInstanceMember &&
           resolvedAst.body == null) {
         // Skip top-level/static fields without an initializer.
         return;
       }
       computeClosureToClassMapping(element, closedWorldRefiner);
     });
@@ skipping 1179 matching lines @@
 ///
 /// Move the below classes to a JS model eventually.
 ///
 abstract class JSEntity implements MemberEntity {
   Local get declaredEntity;
 }
 
 abstract class PrivatelyNamedJSEntity implements JSEntity {
   Entity get rootOfScope;
 }