Gardening: Rebase virtual/threaded/transitions/opacity-transform-transitions-inside-iframe.html on Mac10.6

TBR=ericwilligers@chromium.org

Review URL: https://codereview.chromium.org/260433003

git-svn-id: svn://svn.chromium.org/blink/trunk@172875 bbb929c8-8fbe-4397-9dbb-9b2b20218538