Disable AppsGridControllerTest.FirstPageKeyboardNavigation

This is causing crashes after some re-factoring:
https://code.google.com/p/chromium/issues/detail?id=321284

BUG=321284
TBR=tapted@chromium.org

Review URL: https://codereview.chromium.org/66213011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236042 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236042