> While a browsing context container is marked as inert, its nested browsing context's active document, and all nodes in that Document, must be marked as inert.
(A "browsing context container" is something like a <frame> or <iframe>)
WebKit and Firefox don't do that. Chromium does.
I plan to add a test in https://chromium-review.googlesource.com/c/chromium/src/+/3302812
Closing given bug 236512