PageTransitionEvent

[arbroween]

Hi ! I'm new here but I was using scala.js today and found out that the class definition for PageTransitionEvent was missing from the library. It seems to be a widely supported feature across browsers and should be easy to add. It only inherits from the Event class and add a single persisted property to it.
My source for this is MDN https://developer.mozilla.org/en-US/docs/Web/API/PageTransitionEvent