Drop #16620 patch?

We should check if the behaviour of https://bugzilla.mozilla.org/show_bug.cgi?id=444222 when clearing window.name works for us. If it does, we could backport it to 78 and enable via privacy.window.name.update.enabled = true, and revert our #16620 (closed) patch. #40115 (closed) is related, and might be fixed by this.