It's always enabled when COORDINATED_GRAPHICS is enabled.
Created attachment 363221 [details] Patch
Comment on attachment 363221 [details] Patch r=me as long as bots are happy.
Comment on attachment 363221 [details] Patch Clearing flags on attachment: 363221 Committed r242205: <https://trac.webkit.org/changeset/242205>
All reviewed patches have been landed. Closing bug.
<rdar://problem/48479367>