Define DOM_KEY_LOCATION_* constants on KeyboardEvent

Source/core/dom/KeyboardEvent.h

Index: Source/core/dom/KeyboardEvent.h
diff --git a/Source/core/dom/KeyboardEvent.h b/Source/core/dom/KeyboardEvent.h
index 02c7e34e7770d5e5aecfd08ed26e587498f484a7..a22bc145d05f119acd28769f063ef05a3cdc1747 100644
--- a/Source/core/dom/KeyboardEvent.h
+++ b/Source/core/dom/KeyboardEvent.h
@@ -47,10 +47,13 @@ struct KeyboardEventInit : public UIEventInit {
 class KeyboardEvent : public UIEventWithKeyState {
 public:
     enum KeyLocationCode {
-        DOMKeyLocationStandard      = 0x00,
-        DOMKeyLocationLeft          = 0x01,
-        DOMKeyLocationRight         = 0x02,
-        DOMKeyLocationNumpad        = 0x03
+        DOM_KEY_LOCATION_STANDARD   = 0x00,
+        DOM_KEY_LOCATION_LEFT       = 0x01,
+        DOM_KEY_LOCATION_RIGHT      = 0x02,
+        DOM_KEY_LOCATION_NUMPAD     = 0x03,
+        // FIXME: The following values are not supported yet (crbug.com/265446)
+        DOM_KEY_LOCATION_MOBILE     = 0x04,

[ojan, 2013/07/29 22:09:07]

I think we should pushback on the spec here. What does "mobile" really mean? Is
a tablet mobile? I can't think of anytime we'd want to set this to true.

+        DOM_KEY_LOCATION_JOYSTICK   = 0x05

[ojan, 2013/07/29 22:09:07]

Same here. They gamepad API is for joysticks. Not sure there's any case we'd
return true here.

I'd rather we only expose these once we actually ever return true for it. Then
developers can feature detect whether the browser would ever return these
values.

     };
 
     static PassRefPtr<KeyboardEvent> create()