[Nicosia] Add additional layer state classes, use impl-based approach to make them extendable
Created attachment 346617 [details] Patch
Comment on attachment 346617 [details] Patch Clearing flags on attachment: 346617 Committed r234594: <https://trac.webkit.org/changeset/234594>
All reviewed patches have been landed. Closing bug.
<rdar://problem/42961447>