MediaControlsImpl::RemovedFrom() which is called during a DOM removal mutation calls Hide(), which eventually calls MediaControlLoadingPanelElement::CleanupShadowDOM(), which does another DOM removal. This causes problems with Node::isConnected() not being up-to-date as expected for the inner removal. Ideally, I don't think we should have nested removals like this.

I needed to do a workaround for this for https://chromium-review.googlesource.com/c/chromium/src/+/1149300