Add ability to run async magnitude-perf tests.

Add ability to run async magnitude-perf tests.

I would like to add new time complexity test.
Unfortunately, current framework doesn't support async tests.

In this patch I wrap for and while operators, so they could
run asynchronously.

CL I'm going to write test to (fix n^2 HTML parsing):
https://codereview.chromium.org/494993002/

Here is the first async test:
https://codereview.chromium.org/500363002/

BUG=410790
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=181539

[eustas, 2014-09-04 11:44:24]

eustas@chromium.org changed reviewers:
+ nbarth@chromium.org

[Nils Barth (inactive), 2014-09-04 13:51:41]

Hi Eustas,
Could you give some context for this?
(Code looks fine from quick look.)
Once Ojan's less busy (i.e., not code yellow), could you check with him as well?
Thanks!

[eustas, 2014-09-04 14:39:31]

On 2014/09/04 13:51:41, Nils Barth (inactive) wrote:
> Hi Eustas,
> Could you give some context for this?
> (Code looks fine from quick look.)
> Once Ojan's less busy (i.e., not code yellow), could you check with him as
well?
> Thanks!

Hello.

I've updated description.

Thank you for your attention.

[Nils Barth (inactive), 2014-09-04 14:48:42]

On 2014/09/04 14:39:31, eustas wrote:
> On 2014/09/04 13:51:41, Nils Barth (inactive) wrote:
> > Hi Eustas,
> > Could you give some context for this?
> > (Code looks fine from quick look.)
> > Once Ojan's less busy (i.e., not code yellow), could you check with him as
> well?
> > Thanks!
> 
> Hello.
> 
> I've updated description.
> 
> Thank you for your attention.

Thanks for context Eustas!
(and for fixing the bug that provoked this!)
I'm no JavaScript expert, and I'm not working much on Chrome these days, so
could you get another reviewer?
(Ojan or Eric Seidel should be able to recommend someone if they can't do it
themselves.)

[eustas, 2014-09-05 05:07:49]

eustas@chromium.org changed reviewers:
+ eseidel@chromium.org
- nbarth@chromium.org

[eseidel, 2014-09-05 17:02:22]

The CQ bit was checked by eseidel@chromium.org

[eseidel, 2014-09-05 17:02:23]

lgtm

[commit-bot: I haz the power, 2014-09-05 17:02:39]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/eustas@chromium.org/544453004/40001

[commit-bot: I haz the power, 2014-09-05 17:14:05]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-09-05 17:14:06]

Try jobs failed on following builders:
  linux_chromium_gn_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_chromium_gn_rel/bu...)

[eustas, 2014-09-08 05:39:54]

The CQ bit was checked by eustas@chromium.org

[commit-bot: I haz the power, 2014-09-08 05:41:00]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/eustas@chromium.org/544453004/40001

[commit-bot: I haz the power, 2014-09-08 06:05:21]

Committed patchset #3 (id:40001) as 181539