@reillyeon and I were discussing the Chromium implementation of #68 and we figured it'd be good to get some clarification on how it integrates with Device{Orientation,Motion}Event -- either in terms of what the spec's supposed to mean or, if it's intentionally leaving some decisions up to implementations, what WebKit/Safari do so we can try to align some of the behavior across implementations.

• Does WebKit/Safari remember if permission's been granted to a given page or are users always asked for permission when requestPermission() is called?
• If an event listener for a deviceorientation/motion event is added before permission is granted, does anything happen (e.g. a null deviceorientation/motion event is fired)?
• Are users at all supposed to be able to add an event listener for those events before requesting permission?
• Once permission is granted, do previously registered event listeners start working or does the user need to add another event listener in order to start receiving events?

cc @cdumez