Define DOM_KEY_LOCATION_* constants on KeyboardEvent

Source/core/dom/KeyboardEvent.idl

 /*
  * Copyright (C) 2006 Apple Computer, Inc.
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 [
     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;
+    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    keyLocation;

[Mike West, 2013/07/29 12:40:24]

This isn't really related to this CL, as it's existing behavior, but the spec
lists this as 'location' (no 'key' prefix). What do Gecko and IE do?

Relatedly, 'keyIdentifier' doesn't seem to be specified either, at least, not at
http://www.w3.org/TR/DOM-Level-3-Events/#events-keyboardevents.

[do-not-use, 2013/07/29 12:49:11]

I am already addressing this in:
https://codereview.chromium.org/20034002/

Both Gecko and IE10 support 'location'.

     [InitializedByEventConstructor] readonly attribute boolean          ctrlKey;
     [InitializedByEventConstructor] readonly attribute boolean          shiftKey;
     [InitializedByEventConstructor] readonly attribute boolean          altKey;
     [InitializedByEventConstructor] readonly attribute boolean          metaKey;
     readonly attribute boolean          altGraphKey;
 
     // FIXME: this does not match the version in the DOM spec.
     void initKeyboardEvent([Default=Undefined] optional DOMString type,
                            [Default=Undefined] optional boolean canBubble,
                            [Default=Undefined] optional boolean cancelable,
                            [Default=Undefined] optional Window view,
                            [Default=Undefined] optional DOMString keyIdentifier,
                            [Default=Undefined] optional unsigned long keyLocation,
                            [Default=Undefined] optional boolean ctrlKey,
                            [Default=Undefined] optional boolean altKey,
                            [Default=Undefined] optional boolean shiftKey,
                            [Default=Undefined] optional boolean metaKey,
                            [Default=Undefined] optional boolean altGraphKey);
 };