Suppressions for more flaky layout tests.

BUG=316425,316429
TBR=antonm@chromium.org,yhirano@chromium.org

Review URL: https://codereview.chromium.org/62673003

git-svn-id: svn://svn.chromium.org/blink/trunk@161571 bbb929c8-8fbe-4397-9dbb-9b2b20218538