Gardening: Suppress layout test failures

A lot of layout test failures after r156242.

TBR=ojan@chromium.org
BUG=274667

Review URL: https://codereview.chromium.org/22889010

git-svn-id: svn://svn.chromium.org/blink/trunk@156252 bbb929c8-8fbe-4397-9dbb-9b2b20218538