convert isolates to use Future

tests/isolate/src/MandelIsolateTest.dart

 // 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.
 
 #library("MandelIsolateTest");
 #import('TestFramework.dart');
 
 final TERMINATION_MESSAGE = -1;
 final N = 100;
 final ISOLATES = 20;
@@ skipping 83 matching lines @@
   }
 
   void shutdown() {
     _out.then((SendPort p) {
       p.send(TERMINATION_MESSAGE, null);
     });
   }
 
   MandelbrotState _state;
   int _id;
-  Promise<SendPort> _out;
+  Future<SendPort> _out;
 
 }
 
 
 class LineProcessor extends Isolate {
 
   LineProcessor() : super() { }
 
   void main() {
     this.port.receive((message, SendPort replyTo) {
@@ skipping 31 matching lines @@
       result[x] = i;
     }
     return result;
   }
 
 }
 
 main() {
   runTests([test]);
 }