isolates refactor: this change introduces 'dart:isolate' as a library. This is a

compiler/lib/implementation/isolate.js

 // Copyright (c) 2011, 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.
 
+// TODO(sigmund): this file should be removed when the dart code generation
+// backend is deleted.
+
 var isolate$current = null;
 var isolate$rootIsolate = null;  // Will only be set in the main worker.
 var isolate$inits = [];
 var isolate$globalThis = this;
 
 // These declarations are needed to avoid errors from the Closure Compiler
 // optimizer. They are defined in client/dom/generated/dart_dom_wrapping.js.
 var __dom_wrap;
 var __dom_unwrap;
 
@@ skipping 498 matching lines @@
 }
 
 function isolate$deserializeMessage(message) {
   if (isolate$useWorkers || isolate$useWorkerSerializationProtocol) {
     return native__IsolateJsUtil__deserializeMessage(message);
   } else {
     // Nothing more to do.
     return message;
   }
 }