Create Document exitPointerLock and pointerLockElement API methods.

Source/core/dom/Document.idl

Index: Source/core/dom/Document.idl
diff --git a/Source/core/dom/Document.idl b/Source/core/dom/Document.idl
index bf48b5320d4619f424203eda13de5d23f36d6c60..b20d4f75ea45a4bfd6e187a08517c94360791b2c 100644
--- a/Source/core/dom/Document.idl
+++ b/Source/core/dom/Document.idl
@@ -163,7 +163,9 @@ typedef (CanvasRenderingContext2D or WebGLRenderingContext) RenderingContext;
     readonly attribute DOMString compatMode;
 
     [MeasureAs=PrefixedDocumentExitPointerLock] void webkitExitPointerLock();

[Inactive, 2014/05/12 21:29:29]

We could use [ImplementedAs=exitPointerLock] and rename the method on native
side to avoid having both prefixed / unprefixed methods on native side.

[scheib, 2014/05/12 22:24:09]

Done.

+    [MeasureAs=DocumentExitPointerLock] void exitPointerLock();

[Inactive, 2014/05/12 21:29:29]

Why are we measuring the usage of the unprefixed ones?

[scheib, 2014/05/12 22:24:09]

To consider the eventual migration of usage from the prefixed version of the API
to unprefixed we should measure the prefixed:unprefixed ratio. The API is
critical to only a narrow application set, so we don't anticipate generally
large numbers.

     [MeasureAs=PrefixedDocumentPointerLockElement] readonly attribute Element webkitPointerLockElement;

[Inactive, 2014/05/12 21:29:29]

Ditto ([ImplementedAs]).

[scheib, 2014/05/12 22:24:09]

Done.

+    [MeasureAs=DocumentPointerLockElement] readonly attribute Element pointerLockElement;
 
     // Event handler attributes
     attribute EventHandler onbeforecopy;