Suppressed flaky layout tests.

BUG=316349,316372,316380
TBR=antonm@chromium.org,yhirano@chromium.org

Review URL: https://codereview.chromium.org/61763015

git-svn-id: svn://svn.chromium.org/blink/trunk@161562 bbb929c8-8fbe-4397-9dbb-9b2b20218538