See Darin's comment on this bug: https://bugs.webkit.org/show_bug.cgi?id=224718#c8
Created attachment 426703 [details] Patch
Committed r276386 (236861@main): <https://commits.webkit.org/236861@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 426703 [details].
Re-opened since this is blocked by bug 224912
<rdar://problem/76996754>