Fix call to completer for async closures.

Fix call to completer for async closures.

Addressing comments from https://codereview.chromium.org/460763002/

BUG=
R=srdjan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=39207

[Michael Lippautz (Google), 2014-08-13 16:39:09]

As suggested, I added the opt counter threshold to the test. I checked that the
test fails without the fix when calling the function (and without prohibiting
optimizations in object.cc).

[srdjan, 2014-08-13 16:49:33]

lgtm

https://codereview.chromium.org/467323002/diff/20001/tests/language/async_con...
File tests/language/async_control_structures_test.dart (right):

https://codereview.chromium.org/467323002/diff/20001/tests/language/async_con...
tests/language/async_control_structures_test.dart:70: var asyncReturn;
You can put this in a loop with 10 iterations to make sure that all functions
will be optimized.

[Michael Lippautz (Google), 2014-08-13 17:13:56]

https://codereview.chromium.org/467323002/diff/20001/tests/language/async_con...
File tests/language/async_control_structures_test.dart (right):

https://codereview.chromium.org/467323002/diff/20001/tests/language/async_con...
tests/language/async_control_structures_test.dart:70: var asyncReturn;
On 2014/08/13 16:49:33, srdjan wrote:
> You can put this in a loop with 10 iterations to make sure that all functions
> will be optimized.

Done.

[Michael Lippautz (Google), 2014-08-13 17:14:49]

Committed patchset #3 manually as 39207 (presubmit successful).

[Florian Schneider, 2014-08-14 09:20:33]

LGTM.