nly standard requirement for user
// activation concerns the interaction between iframe elements and their parent
// browsing contexts [1]. Because testdriver.js currently cannot operate within
// an iframe, the standard requirement cannot be used to verify the correctness
// of the `bless` method. Instead, rely on the optional behavior of early exit
// and rejecting in `video.play()` if the media is not "allowed to play". [2]
// Browsers which don't implement this will pass this test spuriously.
//
// [1] 