Ideally, we should find a way to test animations, but for now, make sure that the dumped snapshot matches actual state.
This fixes fast/forms/checkbox-appearance-change-by-checked.html on Yosemite.
Created attachment 232712 [details]
This only did it for WK2.
Created attachment 235083 [details]
Committed the WK1 part in <http://trac.webkit.org/r171193>.