Remove ash_unittests to see if it's affecting bot stability

Bot has been completely failing intermittently. ash_unittests
is the Win8-specific part that runs here, so temporarily remove
it to see if it's related to the back-and-forth to Metro
switches.

BUG=340422

Review URL: https://codereview.chromium.org/411673002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284820 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed