Revert 233486 "disable AcceleratorControllerTest.GlobalAccelerat..."

Wasn't actually flaky, full fix for ash_unittests coming soon.

> disable AcceleratorControllerTest.GlobalAcceleratorsToggleAppList on win aura
> 
> Failing on Win Aura bots flakily for a few days, and now quite a lot. No
> clear regression cause though.
> 
> R=kbr@chromium.org
> TBR=kbr@chromium.org
> BUG=316012
> 
> Review URL: https://codereview.chromium.org/63783002

TBR=scottmg@chromium.org

Review URL: https://codereview.chromium.org/65283003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233709 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233709