Optimize "smi or old" filter in scavenger into a single branch.

Consistently speeds up SplayHarder by ~3-6% on ia32. Impact on ARM varies greatly between runs...

R=iposva@google.com

Review URL: https://codereview.chromium.org//504953002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@39557 260f80e4-7a28-3924-810f-c04153c831b5
Defer execution of the main isolate's entry point until the message loop.

This allows us to know more accurately the stack limit while running main.

R=johnmccutchan@google.com

Review URL: https://codereview.chromium.org//503363002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@39558 260f80e4-7a28-3924-810f-c04153c831b5
Await it!

Add support for awaiting futures. This leaves us with a non-structural CFG.

TODOs:
* Forwarding exceptions through futures in async functions and rethrowing them using await.
* Known bug with nested contexts (will be fixed in following CL)
* await is not recognized at all expressions specified (yet)

BUG=
R=hausner@google.com, srdjan@google.com

Review URL: https://codereview.chromium.org//484933003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@39559 260f80e4-7a28-3924-810f-c04153c831b5
Fix build by excluding await tests from all but the vm.

BUG=

Review URL: https://codereview.chromium.org//504293002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@39560 260f80e4-7a28-3924-810f-c04153c831b5
DEPS AutoUpdate: chromium to 291652 (2014-08-26 20:14:05 +0200) blois@google.com
Adding flags for dart native extension support.
http://src.chromium.org/viewvc/chrome?view=rev&revision=291652

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@39561 260f80e4-7a28-3924-810f-c04153c831b5