I thiiiink I've seen the status of a movie `<outfit-layer>` sometimes
be `loading` even when it's clearly already loaded and running. I
haven't been able to track down where and how that happens exactly, so
this is me acting on a hunch: that maybe the
I-would-have-thought-very-unlikely event that the iframe finishes
loading before the `<outfit-layer>` connects with its children maybe
happens more often than one might think!
In this change, we set up the iframe to receive `requestStatus`
messages, which it responds to with the status immediately. And we send
one of these when the `<outfit-layer>` first discovers the iframe.
Fingers crossed!