Scrolling can drop frames when CoreAnimation commits take a long time
Created attachment 446779 [details] Patch
<rdar://86235740>
Created attachment 446780 [details] Patch
Created attachment 446858 [details] Patch
Committed r286905 (245131@main): <https://commits.webkit.org/245131@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 446858 [details].