We can make the code clearer in places where downcast<KeyframeEffect> is used.
Pull request: https://github.com/WebKit/WebKit/pull/8374
Committed 258639@main (600168ef8d8f): <https://commits.webkit.org/258639@main> Reviewed commits have been landed. Closing PR #8374 and removing active labels.
<rdar://problem/104008134>