Re: Mouse Lock

John Villar and I have produced a draft specification:
https://docs.google.com/document/d/1uV4uDVIe9-8XdVndW8nNGWBfqn9ieeop-5TRfScOG_o/edit?hl=en_US&authkey=CM-dw7QG

Some additional notes included in that draft not yet discussed here:
- .deltaX conflicts with WheelEvent, I've used .movementX/Y instead unless
we feel DOM L3 should be modified.
- I've omitted the call of mouselocklost at a page close or
‘onbeforeunload’, as I can not determine a use case that benefits from it.
- I've omitted the suggestion of cancelLock on a bubbling MouseEvent - as it
is not needed, .target.unlockMouse() can be called.