Update Timer API to take the callback as the last parameter.

samples/actors/core/actors-term.dart

 #library('actors');
 #source('actors.dart');
 #source('actors-interface.dart');
 #source('actors-ui.dart');
 
 class _WindowActor extends Actor {
   _WindowActor() : super() {
     on["print"] = (String m) {
       print("${m}");
     };
 
     /**
      * Sends a message back using the 'reply' parameter after specified number
      * of milliseconds specified by 'timeout' parameter.
      */
     on["setTimeout"] = (Reply reply, int timeout) {
-      new Timer((Timer t) {reply.respond();}, timeout);
+      new Timer(timeout, (Timer t) {reply.respond();});
     };
   }
 }
 
 class _WindowProxyImpl extends _NullWindowProxy {
   ActorId _window;
   _WindowProxyImpl(this._window);
   
   void print(String m) => _window.send("print", [m]);
 
   void setTimeout(Reply t, int timeout) =>
     _window.send("setTimeout", [t, timeout]);
 }