We need to adopt the new AnimatableProperty type in KeyframeList and KeyframeValue.
Once we do that, we also need to change some call sites elsewhere.
Pull request: https://github.com/WebKit/WebKit/pull/7839
Committed 258075@main (eee69004092a): <https://commits.webkit.org/258075@main> Reviewed commits have been landed. Closing PR #7839 and removing active labels.
<rdar://problem/103509079>