Disable KeyboardAccessTest.TestAltMenuKeyboardAccessFocusOmnibox and
KeyboardAccessTest.TestSystemMenuWithKeyboard.  The first one is failing
constantly.  These were enabled in r244831 but judging by the rest of
the commit they were meant to be disabled.

TBR=jam@chromium.org
BUG=330735

Review URL: https://codereview.chromium.org/139693002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244916 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244916