Mark tests as needing manual rebaseline.

These will change expectations once the Chromium side
of the patch lands: https://codereview.chromium.org/53493003.

TBR=jochen
BUG=309760

Review URL: https://codereview.chromium.org/53203004

git-svn-id: svn://svn.chromium.org/blink/trunk@161365 bbb929c8-8fbe-4397-9dbb-9b2b20218538