https://drafts.csswg.org/css-text-3/#conditionally-hang
Created attachment 432869 [details] Patch
Created attachment 432884 [details] Patch
Committed r279568 (239399@main): <https://commits.webkit.org/239399@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 432884 [details].
<rdar://problem/80177629>