In particular: 

* consumption-sameorigin.html - it's same origin, so it doesn't need to use postMessage()!
* propagation-crossorigin.sub.html - the current structure is way too hard to follow. It should just use async/await. 

Further, propagation-crossorigin.sub.html makes a number of incorrect assumptions: it seems to assume that hasBeenActive gets reflected across origins. That's wrong per the HTML spec (or at least my reading of "activation notification").
https://html.spec.whatwg.org/#activation-notification


which says it only applies same origin.