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

samples/tests/samples/src/proxy/PromiseBasedTest.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("PromiseBasedTest");
+#import("dart:isolate");
 #import("../../../../proxy/promise.dart");
 #import("../../../../../tests/isolate/src/TestFramework.dart");
 
 class TestIsolate extends Isolate {
 
   TestIsolate() : super();
 
   void main() {
     int seed = 0;
     this.port.receive((var message, SendPort replyTo) {
@@ skipping 60 matching lines @@
   expect.completes(completer.future).then((int value) {
     //print("expect 2: $value");
     Expect.equals(99, value);
     expect.succeeded();
   });
 }
 
 void main() {
   runTests([test, expandedTest]);
 }