When includeSubframes is set to true, WebKit never stops observing new content even when the main frame navigates.
Pull request: https://github.com/WebKit/WebKit/pull/16090
Committed 266308@main (e2372fbf8b4b): <https://commits.webkit.org/266308@main> Reviewed commits have been landed. Closing PR #16090 and removing active labels.
<rdar://problem/112874225>