Creating a ticket for this -- it's actually not so trivial due to a domino effect of things that need to be included.
Created attachment 360186 [details] Patch
Created attachment 360351 [details] Patch
Created attachment 360353 [details] Patch
Created attachment 360357 [details] Patch
Comment on attachment 360357 [details] Patch Clearing flags on attachment: 360357 Committed r240600: <https://trac.webkit.org/changeset/240600>
All reviewed patches have been landed. Closing bug.
<rdar://problem/47608798>