Changes

# <strike>"Events that require the concept of a mouse cursor must not be dispatched (for example: mouseover, mouseout)"</strike> - humph

# "When unlocked, the system cursor can exit and re-enter the user agent window. If it does so and the user agent was not the target of operating system mouse move events then the most recent mouse position will be unknown to the user agent and movementX/Y can not be computed and must be set to zero"

# <strike>Figure out [[Mac Crash with Jesse's SynthesizeMouseMove change]]</strike> humph

# <strike>When the locked element is removed from the DOM Tree, the mouse should be unlocked</strike> diogogmt

=====Out of Scope Implementation=====

# The ESC key should exit mouse lock. This will currently exit fullscreen, and therefore mouse lock - diogogmt

# "Once mouse lock is acquired, stop mouse events from being fired to other elements that are not locked (e.g., only fire to locked element)." Only the fullscreen element will get events.

# "User agents may prompt for confirmation before locking, this preference may be saved as a content setting" How to deal with this? What UI do we use? See also, "Repeated escapes of mouse lock can signal user agent to not re-lock the mouse without more specific user intent gesture, e.g. similar to how Chrome suppresses repeated alert() calls"

====Tests====