Mark a test as flaky and remove some extraneous comment lines.

BUG=373072
TBR=dpranke@chromium.org

Review URL: https://codereview.chromium.org/287803002

git-svn-id: svn://svn.chromium.org/blink/trunk@173995 bbb929c8-8fbe-4397-9dbb-9b2b20218538