Extract ClosedWorldImpl from WorldImpl.

pkg/compiler/lib/src/enqueue.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 dart2js.enqueue;
 
 import 'dart:collection' show Queue;
 
 import 'cache_strategy.dart';
 import 'common/backend_api.dart' show Backend;
@@ skipping 146 matching lines @@
       Resolution resolution,
       this.strategy,
       this._globalDependencies,
       Backend backend,
       CacheStrategy cacheStrategy,
       [this.name = 'resolution enqueuer'])
       : this.backend = backend,
         this._resolution = resolution,
         this.nativeEnqueuer = backend.nativeResolutionEnqueuer(),
         _universe = new ResolutionWorldBuilderImpl(
-            backend, resolution, cacheStrategy, const TypeMaskStrategy()) {
+            backend, resolution, cacheStrategy, const OpenWorldStrategy()) {
     _impactVisitor = new EnqueuerImplImpactVisitor(this);
   }
 
   ResolutionWorldBuilder get universe => _universe;
 
   OpenWorld get _openWorld => universe.openWorld;
 
   bool get queueIsEmpty => _queue.isEmpty;
 
   DiagnosticReporter get _reporter => _resolution.reporter;
@@ skipping 346 matching lines @@
 }
 
 typedef void _DeferredActionFunction();
 
 class _DeferredAction {
   final Element element;
   final _DeferredActionFunction action;
 
   _DeferredAction(this.element, this.action);
 }