Extract ClosedWorldRefiner implementation from ClosedWorldImpl to ClosedWorldBase

pkg/compiler/lib/src/js_backend/enqueuer.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.js.enqueue;
 
 import 'dart:collection' show Queue;
 
 import '../common/codegen.dart' show CodegenWorkItem;
 import '../common/tasks.dart' show CompilerTask;
@@ skipping 33 matching lines @@
   bool queueIsClosed = false;
   final CompilerTask task;
   final EnqueuerListener listener;
   final CompilerOptions _options;
 
   WorldImpactVisitor _impactVisitor;
 
   final Queue<WorkItem> _queue = new Queue<WorkItem>();
 
   /// All declaration elements that have been processed by codegen.
-  final Set<Entity> _processedEntities = new Set<Entity>();
+  final Set<MemberEntity> _processedEntities = new Set<MemberEntity>();
 
   static const ImpactUseCase IMPACT_USE =
       const ImpactUseCase('CodegenEnqueuer');
 
   CodegenEnqueuer(this.task, this._options, this.strategy, this._worldBuilder,
       this._workItemBuilder, this.listener)
       : this.name = 'codegen enqueuer' {
     _impactVisitor = new EnqueuerImplImpactVisitor(this);
   }
 
@@ skipping 187 matching lines @@
   void logSummary(void log(String message)) {
     log('Compiled ${_processedEntities.length} methods.');
     listener.logSummary(log);
   }
 
   String toString() => 'Enqueuer($name)';
 
   ImpactUseCase get impactUse => IMPACT_USE;
 
   @override
-  Iterable<Entity> get processedEntities => _processedEntities;
+  Iterable<MemberEntity> get processedEntities => _processedEntities;
 
   @override
   Iterable<ClassEntity> get processedClasses => _worldBuilder.processedClasses;
 }
 
 /// Builder that creates the work item necessary for the code generation of a
 /// [MemberElement].
 class CodegenWorkItemBuilder extends WorkItemBuilder {
   JavaScriptBackend _backend;
   CompilerOptions _options;
@@ skipping 11 matching lines @@
     // code for checked setters.
     if (element.isField && element.isInstanceMember) {
       if (!_options.enableTypeAssertions ||
           element.enclosingElement.isClosure) {
         return null;
       }
     }
     return new CodegenWorkItem(_backend, element);
   }
 }