Suppress ASSERTs that are trigging on ChromeOS browser tests

TBR=dstockwell@chromium.org
BUG=342478

Review URL: https://codereview.chromium.org/153043006

git-svn-id: svn://svn.chromium.org/blink/trunk@166873 bbb929c8-8fbe-4397-9dbb-9b2b20218538