[rAC, OSX] Enable browser test for AutofillDialog

This enables the final remaining AutofillDialogControllerTest for OSX.

BUG=256864
R=isherman@chromium.org

Review URL: https://codereview.chromium.org/25394002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226185 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226185