Finish strong mode cleaning of dart2js.

pkg/compiler/lib/src/universe/class_set.dart

 // Copyright (c) 2015, 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.world.class_set;
 
 import 'dart:collection' show IterableBase;
 
 import '../elements/elements.dart' show ClassElement;
 import '../elements/entities.dart' show ClassEntity;
@@ skipping 348 matching lines @@
     if (isIndirectlyInstantiated) {
       sb.write(' indirectly');
     }
     if (isAbstractlyInstantiated) {
       sb.write(' abstractly');
     }
     sb.write(' [');
     if (_directSubclasses.isEmpty) {
       sb.write(']');
     } else {
-      var subclasses = _directSubclasses;
+      dynamic subclasses = _directSubclasses;
       if (sorted) {
         subclasses = _directSubclasses.toList()
           ..sort((a, b) {
             return a.cls.name.compareTo(b.cls.name);
           });
       }
       bool needsComma = false;
       for (ClassHierarchyNode child in subclasses) {
         if (instantiatedOnly && !child.isInstantiated) {
           continue;
@@ skipping 538 matching lines @@
   STOP,
 
   /// Iteration skips the subclasses of the current class.
   SKIP_SUBCLASSES,
 }
 
 /// Visiting function used for the `forEachX` functions of [ClassHierarchyNode]
 /// and [ClassSet]. The return value controls the continued iteration. If `null`
 /// is returned, iteration continues to the end.
 typedef IterationStep ForEachFunction(ClassEntity cls);