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

tests/standalone/src/io/MultipleTimerTest.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
 #import("dart:io");
 
 class MultipleTimerTest {
 
   static final int TIMEOUT1 = 1000;
   static final int TIMEOUT2 = 2000;
   static final int TIMEOUT3 = 500;
@@ skipping 30 matching lines @@
     }
 
     _order = new List<int>(4);
     _order[0] = 2;
     _order[1] = 0;
     _order[2] = 3;
     _order[3] = 1;
     _message = 0;
 
     _startTime1 = (new Date.now()).value;
-    new Timer(timeoutHandler1, TIMEOUT1);
+    new Timer(TIMEOUT1, timeoutHandler1);
     _startTime2 = (new Date.now()).value;
-    new Timer(timeoutHandler2, TIMEOUT2);
+    new Timer(TIMEOUT2, timeoutHandler2);
     _startTime3 = (new Date.now()).value;
-    new Timer(timeoutHandler3, TIMEOUT3);
+    new Timer(TIMEOUT3, timeoutHandler3);
     _startTime4 = (new Date.now()).value;
-    new Timer(timeoutHandler4, TIMEOUT4);
+    new Timer(TIMEOUT4, timeoutHandler4);
   }
 
   static void testMain() {
     testMultipleTimer();
   }
 
   static int _startTime1;
   static int _startTime2;
   static int _startTime3;
   static int _startTime4;
   static List<int> _order;
   static int _message;
 }
 
 main() {
   MultipleTimerTest.testMain();
 }