Added suppressions for flaky failures and possibly expected failures.

BUG=374936,376432
TBR=alph@chromium.org

Review URL: https://codereview.chromium.org/292813010

git-svn-id: svn://svn.chromium.org/blink/trunk@174590 bbb929c8-8fbe-4397-9dbb-9b2b20218538