Add new Pointer Lock spec events webkitpointerlockchange and webkitpointerlockerror

https://bugs.webkit.org/show_bug.cgi?id=88377

Reviewed by Dimitri Glazkov.

Part of a series of refactoring changes to update pointer lock API to
the fullscreen locking style. https://bugs.webkit.org/show_bug.cgi?id=84402

New change and error events added. Follow up patches will remove
the previous callbacks and pointerlocklost event. Tests updated
to include the new events, and a new test added specifically for
the new events, pointerlockchange-pointerlockerror-events.html.

Source/WebCore:

Test: pointer-lock/pointerlockchange-pointerlockerror-events.html

* dom/Document.h:
(Document):
* dom/Document.idl:
* dom/EventNames.h:
(WebCore):
* page/PointerLockController.cpp:
(WebCore::PointerLockController::requestPointerLock):
(WebCore::PointerLockController::didAcquirePointerLock):
(WebCore::PointerLockController::didNotAcquirePointerLock):
(WebCore::PointerLockController::didLosePointerLock):
(WebCore::PointerLockController::enqueueEvent):
(WebCore):
* page/PointerLockController.h:
(PointerLockController):

LayoutTests:

* pointer-lock/lock-already-locked-expected.txt:
* pointer-lock/lock-already-locked.html:
* pointer-lock/pointer-lock-api-expected.txt:
* pointer-lock/pointer-lock-api.html:
* pointer-lock/pointerlockchange-pointerlockerror-events-expected.txt: Added.
* pointer-lock/pointerlockchange-pointerlockerror-events.html: Added.
* pointer-lock/pointerlocklost-event-expected.txt:
* pointer-lock/pointerlocklost-event.html:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@119763 268f45cc-cd09-0410-ab3c-d52691b4dbfc