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

tests/isolate/src/APIv2_unresolvedPortsStandaloneNegativeTest.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.
 
 // A negative test to ensure we are covering all the assertions and running to
 // completion APIv2_unresolvedPortsStandaloneTest.
 #library('unresolved_ports');
+#import('dart:isolate');
 
 bethIsolate(ReceivePort port) {
   port.receive((msg, reply) => msg[1].send(
         "${msg[0]}\nBeth says: Tim are you coming? And Bob?", reply));
 }
 
 timIsolate(ReceivePort port) {
   Isolate2 bob = new Isolate2.fromCode(bobIsolate);
   port.receive((msg, reply) => bob.sendPort.send(
         "$msg\nTim says: Can you tell 'main' that we are all coming?", reply));
@@ skipping 16 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());
 }