Revert "Revert "Removing setImmediate and hiding WindowTimers interface""

Issue was that requestAnimationFrame got removed from Dartium during a merge conflict :(

BUG=
R=efortuna@google.com

Review URL: https://codereview.chromium.org//27441002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@28700 260f80e4-7a28-3924-810f-c04153c831b5
9 files changed