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

runtime/bin/timer.dart

Index: runtime/bin/timer.dart
diff --git a/runtime/bin/timer.dart b/runtime/bin/timer.dart
index c5be36f040356c147854c5bfc1fd537d47ba12c3..d3fe635c7cdf67bdf7d35dbf4bf5441b42033591 100644
--- a/runtime/bin/timer.dart
+++ b/runtime/bin/timer.dart
@@ -7,13 +7,13 @@ interface Timer default _Timer{
    * Creates a new timer. The [callback] callback is invoked after
    * [milliSeconds] milliseconds.
    */
-  Timer(void callback(Timer timer), int milliSeconds);
+  Timer(int milliSeconds, void callback(Timer timer));
 
   /**
    * Creates a new repeating timer. The [callback] is invoked every
    * [milliSeconds] millisecond until cancelled.
    */
-  Timer.repeating(void callback(Timer timer), int milliSeconds);
+  Timer.repeating(int milliSeconds, void callback(Timer timer));
 
   /**
    * Cancels the timer.