Add experimental Support for DOM3 KeyboardEvent key value

public/web/WebInputEvent.h

Index: public/web/WebInputEvent.h
diff --git a/public/web/WebInputEvent.h b/public/web/WebInputEvent.h
index d212f6fe2a2a0e21cde6fe3a232b960849b1cad0..59dcc8604bc77f1ad42323c0b632da1f4f88a733 100644
--- a/public/web/WebInputEvent.h
+++ b/public/web/WebInputEvent.h
@@ -256,6 +256,10 @@ public:
     // code enum are defined in ui/events/keycodes/dom4/keycode_converter_data.h.
     int domCode;
 
+    // The DOM key enum of the key pressed as passed by the embedder. DOM
+    // key enum are defined in ui/events/keycodes/dom3/dom_key_data.h
+    int domKey;
+
     // This identifies whether this event was tagged by the system as being
     // a "system key" event (see
     // http://msdn.microsoft.com/en-us/library/ms646286(VS.85).aspx for