Make the repeating argument to timers optional.

tests/standalone/src/TimerCancelTest.dart

 // Copyright (c) 2011, 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.
 
 class TimerCancelTest {
 
   static void testSimpleTimer() {
 
     void timeoutHandlerUnreachable(Timer timer) {
       Expect.equals(true, false);
     }
 
     void timeoutHandler(Timer timer) {
       cancelTimer.cancel();
     }
 
     void timeoutHandlerRepeat(Timer timer) {
       repeatTimer++;
       timer.cancel();
       Expect.equals(true, repeatTimer == 1);
     }
 
-     cancelTimer = new Timer(timeoutHandlerUnreachable, 1000, false);
+     cancelTimer = new Timer(timeoutHandlerUnreachable, 1000);
      cancelTimer.cancel();
-     new Timer(timeoutHandler, 1000, false);
-     cancelTimer = new Timer(timeoutHandlerUnreachable, 2000, false);
+     new Timer(timeoutHandler, 1000);
+     cancelTimer = new Timer(timeoutHandlerUnreachable, 2000);
      repeatTimer = 0;
-     new Timer(timeoutHandlerRepeat, 1500, true);
+     new Timer.repeating(timeoutHandlerRepeat, 1500);
   }
 
   static void testMain() {
     testSimpleTimer();
   }
 
   static Timer cancelTimer;
   static int repeatTimer;
 }
 
 main() {
   TimerCancelTest.testMain();
 }