Revert of Remove prefixed Pointer Lock API.

LayoutTests/pointer-lock/mouse-event-delivery-prefixed-expected.txt

+Test mouse events are routed to lock target.
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS document.onwebkitpointerlockchange event received.
+PASS document.webkitPointerLockElement is targetdiv1
+     With a lock in place send a click.
+PASS event type: mousedown, target: target1, received on: target1
+PASS event type: mousedown, target: target1, received on: body
+PASS document.onwebkitpointerlockchange event received.
+PASS document.webkitPointerLockElement is targetdiv2
+     With a lock in place send a click.
+PASS event type: mousedown, target: target2, received on: target2
+PASS event type: mousedown, target: target2, received on: body
+     Ensure double clicks work as expected, sending 4 clicks.
+     Creating a click and dblclick.
+PASS event type: mousedown, target: target2, received on: target2
+PASS event type: mouseup, target: target2, received on: target2
+PASS event type: click, target: target2, received on: target2
+PASS event type: mousedown, target: target2, received on: target2
+PASS event type: mouseup, target: target2, received on: target2
+PASS event type: click, target: target2, received on: target2
+PASS event type: dblclick, target: target2, received on: target2
+     Ensuring no false dblclicks if we continue.
+PASS event type: mousedown, target: target2, received on: target2
+PASS event type: mouseup, target: target2, received on: target2
+PASS event type: click, target: target2, received on: target2
+PASS event type: mousedown, target: target2, received on: target2
+PASS event type: mouseup, target: target2, received on: target2
+PASS event type: click, target: target2, received on: target2
+PASS successfullyParsed is true
+
+TEST COMPLETE
+