Rework Timer interface.

sdk/lib/async/future.dart

 // 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.
 
 part of dart.async;
 
 /**
  * A [Future] represents a delayed computation. It is used to obtain a not-yet
  * available value, or error, sometime in the future.  Receivers of a
  * [Future] can register callbacks that handle the value or error once it is
@@ skipping 24 matching lines @@
  *       });
  *
  * If a future does not have a successor but is completed with an error, it
  * forwards the error message to the global error-handler. This special casing
  * makes sure that no error is silently dropped. However, it also means that
  * error handlers should be installed early, so that they are present as soon
  * as a future is completed with an error. The following example demonstrates
  * this potential bug:
  *
  *     var future = getFuture();
- *     new Timer(5, (_) {
+ *     new Timer(new Duration(milliseconds: 5), () {
  *       // The error-handler is only attached 5ms after the future has been
  *       // received. If the future fails in the mean-time it will forward the
  *       // error to the global error-handler, even though there is code (just
  *       // below) to handle the error.
  *       future.then((value) { useValue(value); },
  *                   onError: (e) { handleError(e); });
  *     });
  *
  * In general we discourage registering the two callbacks at the same time, but
  * prefer to use [then] with one argument (the value handler), and to use
@@ skipping 290 matching lines @@
    * The argument [exception] should not be `null`.
    *
    * If [exception] is an [AsyncError], it is used directly as the error
    * message sent to the future's listeners, and [stackTrace] is ignored.
    *
    * Otherwise the [exception] and an optional [stackTrace] is combined into an
    * [AsyncError] and sent to this future's listeners.
    */
   void completeError(Object exception, [Object stackTrace]);
 }