Very simple version of Isolates.

sdk/lib/io/timer_impl.dart

 // Copyright (c) 2013, 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.
 
 part of dart.io;
 
 class _Timer extends LinkedListEntry<_Timer> implements Timer {
   // Disables the timer.
   static const int _NO_TIMER = -1;
 
@@ skipping 146 matching lines @@
           }
         }
       } finally {
         _handling_callbacks = false;
         _notifyEventHandler();
       }
     }
 
     if(_receivePort == null) {
       _receivePort = new ReceivePort();
-      _receivePort.receive((var message, ignored) {
+      _receivePort.listen((var message) {
         _handleTimeout();
       });
     }
   }
 
   void _shutdownTimerHandler() {
     _receivePort.close();
     _receivePort = null;
   }
 }
 
 // Provide a closure which will allocate a Timer object to be able to hook
 // up the Timer interface in dart:isolate with the implementation here.
 _getTimerFactoryClosure() {
   return (int milliSeconds, void callback(Timer timer), bool repeating) {
     if (repeating) {
       return new _Timer.periodic(milliSeconds, callback);
     }
     return new _Timer(milliSeconds, callback);
   };
 }