Change Future.timeout callback to a named parameter.

sdk/lib/io/timer_impl.dart

 // Copyright (c) 2013, 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.
 
 part of dart.io;
 
 class _Timer extends LinkedListEntry<_Timer> implements Timer {
   // Disables the timer.
   static const int _NO_TIMER = -1;
 
   // Timers are ordered by wakeup time.
   static LinkedList<_Timer> _timers = new LinkedList<_Timer>();
 
   static RawReceivePort _receivePort;
   static bool _handling_callbacks = false;
 
   Function _callback;
   int _milliSeconds;
   int _wakeupTime = 0;
 
   static Timer _createTimer(void callback(Timer timer),
                             int milliSeconds,
                             bool repeating) {
     _Timer timer = new _Timer._internal();
     timer._callback = callback;
     if (milliSeconds > 0) {
+      // Add one because DateTime.now() is assumed to round down
+      // to nearest millisecond, not up, so that time + duration is before
+      // duration milliseconds from now. Using micosecond timers like
+      // Stopwatch allows detecting that the timer fires early.
       timer._wakeupTime =
-          new DateTime.now().millisecondsSinceEpoch + milliSeconds;
+          new DateTime.now().millisecondsSinceEpoch + 1 + milliSeconds;
     }
     timer._milliSeconds = repeating ? milliSeconds : -1;
     timer._addTimerToList();
     if (identical(timer, _timers.first)) {
       // The new timer is the first in queue. Update event handler.
       timer._notifyEventHandler();
     }
     return timer;
   }
 
@@ skipping 149 matching lines @@
 _getTimerFactoryClosure() {
   return (int milliSeconds, void callback(Timer timer), bool repeating) {
     if (repeating) {
       return new _Timer.periodic(milliSeconds, callback);
     }
     return new _Timer(milliSeconds, callback);
   };
 }