Revert "Unify dart:isolate."

lib/isolate/timer_hook.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.
 
-interface Timer default _TimerFactory {
-  /**
-   * Creates a new timer. The [callback] callback is invoked after
-   * [milliSeconds] milliseconds.
-   */
-  Timer(int milliSeconds, void callback(Timer timer));
-
-  /**
-   * Creates a new repeating timer. The [callback] is invoked every
-   * [milliSeconds] millisecond until cancelled.
-   */
-  Timer.repeating(int milliSeconds, void callback(Timer timer));
-
-  /**
-   * Cancels the timer.
-   */
-  void cancel();
-}
-
-// TODO(ajohnsen): Patch timer once we have support for patching named
-//                 factory constructors in the VM.
-
 typedef Timer _TimerFactoryClosure(int milliSeconds,
                                    void callback(Timer timer),
                                    bool repeating);
 
 // _TimerFactory provides a hook which allows various implementations of this
 // library to provide a concrete class for the Timer interface.
 class _TimerFactory {
+
   factory Timer(int milliSeconds, void callback(Timer timer)) {
     if (_factory == null) {
       throw new UnsupportedOperationException("Timer interface not supported.");
     }
     return _factory(milliSeconds, callback, false);
   }
 
   factory Timer.repeating(int milliSeconds, void callback(Timer timer)) {
     if (_factory == null) {
       throw new UnsupportedOperationException("Timer interface not supported.");
     }
     return _factory(milliSeconds, callback, true);
   }
 
   static _TimerFactoryClosure _factory;
 }
 
 void _setTimerFactoryClosure(_TimerFactoryClosure closure) {
   _TimerFactory._factory = closure;
 }