Orca does not announce the `moz-message-bar` content as an alert. Covered in [bugzilla bug 1895857](https://bugzilla.mozilla.org/show_bug.cgi?id=1895857). This means that the download warning, which we want to convert to `moz-message-bar` in https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/41820, will not work well with Orca. I'll see what works for us, and I'll push for a solution upstream as well.