Populates sourceDevice attribute into KeyboardEvent

Source/core/events/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,
@@ skipping 33 matching lines @@
     // FIXME: this does not match the version in the spec.
     [CallWith=ScriptState] 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 location,
                            [Default=Undefined] optional boolean ctrlKey,
                            [Default=Undefined] optional boolean altKey,
                            [Default=Undefined] optional boolean shiftKey,
-                           [Default=Undefined] optional boolean metaKey);
+                           [Default=Undefined] optional boolean metaKey,
+                           [Default=Undefined] optional InputDevice? sourceDevice);
 
     // https://w3c.github.io/uievents/#KeyboardEvent-supplemental-interface
     readonly attribute long charCode;
     readonly attribute long keyCode;
     readonly attribute long which;
 
     // Non-standard APIs
     [Measure] readonly attribute DOMString keyIdentifier;
     [ImplementedAs=location, DeprecateAs=KeyboardEventKeyLocation] readonly attribute unsigned long keyLocation;
 };