- Reduce the amount of messages being sent for Timer.run(). - Fast exit for empty timer queues.
- Reduce the amount of messages being sent for Timer.run().
- Fast exit for empty timer queues.

R=sgjesse@google.com, zra@google.com

Review URL: https://codereview.chromium.org//858973002

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@43015 260f80e4-7a28-3924-810f-c04153c831b5

dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk