I've noticed this a few times before, never bothered me enough to fix it until I was working on <https://bugs.webkit.org/show_bug.cgi?id=199837>.
Created attachment 374261 [details] Patch
Comment on attachment 374261 [details] Patch Clearing flags on attachment: 374261 Committed r247503: <https://trac.webkit.org/changeset/247503>
All reviewed patches have been landed. Closing bug.
<rdar://problem/53187017>