[web-animations] mask-type should support discrete animation
Created attachment 454461 [details] Patch
Created attachment 454476 [details] [fast-cq] Patch for landing
Committed r291158 (248318@main): <https://commits.webkit.org/248318@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 454476 [details].
<rdar://problem/90157067>