Changes

''cpearce: We are considering dispatching a "fullscreendenied" event when requests for full-screen are denied. We changed to an "ask forgiveness" model, rather than an "ask permission" model, so requests can be approved/denied immediately in requestFullScreen(). UAs which choose to implement requestFullScreen with an "ask permission" model may never end up sending a "fullscreendenied" event however.''

''cpearce: Acutally, we don't really need that since requestFullScreen() is currently synchronous, so users can just check document.mozFullScreen after calling requestFullScreen(), and if false they know their request has been denied.''