Add Future.timeout.

sdk/lib/async/future.dart

Index: sdk/lib/async/future.dart
diff --git a/sdk/lib/async/future.dart b/sdk/lib/async/future.dart
index 593a775d7f59461f7cda8dcc6cacabb4b316faae..1c273174ffda0504d560880de2b4be5ccd0d037d 100644
--- a/sdk/lib/async/future.dart
+++ b/sdk/lib/async/future.dart
@@ -408,6 +408,17 @@ abstract class Future<T> {
    * its subscribers. The stream closes after the completion value.
    */
   Stream<T> asStream();
+
+  /**
+   * Time-out the future computation after [timeLimit] has passed.
+   *
+   * Returns a new future that completes with the same value as this future,
+   * if this future completes in time.
+   * If this future does not complete before `timeLimit` has passed,

[floitsch, 2013/11/27 12:31:16]

New line before?

[Lasse Reichstein Nielsen, 2013/11/27 12:54:20]

Done.

+   * the [onTimeout] action is executed instead, and its result (whether it
+   * returns or thorws) is used as the result of the returned future.

[floitsch, 2013/11/27 12:31:16]

throws

[Lasse Reichstein Nielsen, 2013/11/27 12:54:20]

Done.

+   */
+  Future timeout(Duration timeLimit, onTimeout());

[floitsch, 2013/11/27 12:31:16]

I think onTimeout should be optional.

[Lasse Reichstein Nielsen, 2013/11/27 12:54:20]

Done.

 }
 
 /**