Rebaseline and optimize Mac image results post Chromium r264636

BUG=363772
TBR=danakj@chromium.org

Review URL: https://codereview.chromium.org/242893002

git-svn-id: svn://svn.chromium.org/blink/trunk@171938 bbb929c8-8fbe-4397-9dbb-9b2b20218538