AlternativePresentationButtonSubstitution::unapply() may not undo substitution.
<rdar://problem/35800599>
Created attachment 328157 [details] Patch and layout test
Comment on attachment 328157 [details] Patch and layout test Clearing flags on attachment: 328157 Committed r225431: <https://trac.webkit.org/changeset/225431>
All reviewed patches have been landed. Closing bug.