Define DOM_KEY_LOCATION_* constants on KeyboardEvent

Source/core/dom/KeyboardEvent.idl

Index: Source/core/dom/KeyboardEvent.idl
diff --git a/Source/core/dom/KeyboardEvent.idl b/Source/core/dom/KeyboardEvent.idl
index 26e48c3744e9849927ed5e0d63059326501f8c69..81b2c171dbe2676f789dad5428fb11740c1ae8af 100644
--- a/Source/core/dom/KeyboardEvent.idl
+++ b/Source/core/dom/KeyboardEvent.idl
@@ -21,6 +21,14 @@
 [
     ConstructorTemplate=Event
 ] interface KeyboardEvent : UIEvent {
+    const unsigned long DOM_KEY_LOCATION_STANDARD = 0x00;
+    const unsigned long DOM_KEY_LOCATION_LEFT     = 0x01;
+    const unsigned long DOM_KEY_LOCATION_RIGHT    = 0x02;
+    const unsigned long DOM_KEY_LOCATION_NUMPAD   = 0x03;
+    // FIXME: The following constants are defined in the specification but
+    // not yet supported (crbug.com/265446).
+    // const unsigned long DOM_KEY_LOCATION_MOBILE   = 0x04;
+    // const unsigned long DOM_KEY_LOCATION_JOYSTICK = 0x05;
 
     [InitializedByEventConstructor] readonly attribute DOMString        keyIdentifier;
     [InitializedByEventConstructor] readonly attribute unsigned long    location;