Model Document should not be enabled anywhere. It's currently following SEPARATED_MODEL.
<rdar://problem/100232590>
Pull request: https://github.com/WebKit/WebKit/pull/5064
Committed 255235@main (d3be2f06a2a2): <https://commits.webkit.org/255235@main> Reviewed commits have been landed. Closing PR #5064 and removing active labels.