Move remaining functionality from ClassWorld to ClosedWorld

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/backend_api.dart' show Backend;
 import '../common/codegen.dart' show CodegenWorkItem;
@@ skipping 70 matching lines @@
   CodegenUniverse get universe => _universe;
 
   Backend get backend => _compiler.backend;
 
   CompilerOptions get options => _compiler.options;
 
   Registry get globalDependencies => _compiler.globalDependencies;
 
   Registry get mirrorDependencies => _compiler.mirrorDependencies;
 
-  ClassWorld get _world => _compiler.closedWorld;
+  ClosedWorld get _world => _compiler.closedWorld;
 
   bool get queueIsEmpty => queue.isEmpty;
 
   /// Returns [:true:] if this enqueuer is the resolution enqueuer.
   bool get isResolutionQueue => false;
 
   QueueFilter get filter => _compiler.enqueuerFilter;
 
   DiagnosticReporter get reporter => _compiler.reporter;
 
@@ skipping 598 matching lines @@
   @override
   void visitStaticUse(StaticUse staticUse) {
     enqueuer.registerStaticUse(staticUse);
   }
 
   @override
   void visitTypeUse(TypeUse typeUse) {
     enqueuer.registerTypeUse(typeUse);
   }
 }