The animation into and out of full screen mode currently lives in WebKit. Instead of duplicating code into WebKit2, the animation code should be moved down into WebCore. Add new APIs to trigger the fullscreen animation and report the animation status back up to WebKit and WebKit2.
Created attachment 85133 [details] Patch
Comment on attachment 85133 [details] Patch Removing r? for now; I think the Document::beginEnterFullScreenAnimation may end up being unnecessary.
It looks like animation won't be moved into WebCore, due to the fact that generated renderers cannot (currently) animate.