When the promises are resolved relative to everything else that happens is observable, and probably needs to be defined. With requestFullscreen() this is pretty complicated and still not properly implemented everywhere, hopefully you can get it right from the start with something simpler and shared web-platform-tests.
https://w3c.github.io/webvr/#dom-vrdisplay-requestpresent https://w3c.github.io/webvr/#dom-vrdisplay-exitpresent
When the promises are resolved relative to everything else that happens is observable, and probably needs to be defined. With
requestFullscreen()
this is pretty complicated and still not properly implemented everywhere, hopefully you can get it right from the start with something simpler and shared web-platform-tests.