Oilpan: fix build after animation changes.

TBR=haraken@chromium.org, shans@chromium.org

Review URL: https://codereview.chromium.org/225303012

git-svn-id: svn://svn.chromium.org/blink/trunk@170952 bbb929c8-8fbe-4397-9dbb-9b2b20218538