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

tests/isolate/src/APIv2_unresolvedPortsBrowserTest.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.
 
 // spawns multiple isolates and sends unresolved ports between them.
 #library('unresolved_ports');
+#import("dart:dom"); // import added so test.dart can treat this as a webtest.
+#import('dart:isolate');
 #import("../../../client/testing/unittest/unittest.dart");
-#import("dart:dom"); // import added so test.dart can treat this as a webtest.
 
 // This is similar as SpawnFromCodeAPIv2Test but using 'unittest.dart' so it can
 // run to completion in browsers.
 
 bethIsolate(ReceivePort port) {
   port.receive((msg, reply) => msg[1].send(
         "${msg[0]}\nBeth says: Tim are you coming? And Bob?", reply));
 }
 
 timIsolate(ReceivePort port) {
@@ skipping 22 matching lines @@
     Isolate2 tim = new Isolate2.fromCode(timIsolate);
     Isolate2 beth = new Isolate2.fromCode(bethIsolate);
 
     beth.sendPort.send(
         // because tim is created asynchronously, here we are sending an
         // unresolved port:
         ["main says: Beth, find out if Tim is coming.", tim.sendPort],
         port.toSendPort());
   });
 }