Resync web-platform-tests/web-animations from upstream.
Created attachment 404610 [details] Patch
Comment on attachment 404610 [details] Patch r=me
Committed r264554: <https://trac.webkit.org/changeset/264554> All reviewed patches have been landed. Closing bug and clearing flags on attachment 404610 [details].
<rdar://problem/65749891>