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 c9e73c03e601bcf2e32b372c05ea2c2ca29eea13..173f6140630759b29cf1b5cc6c1f0316ad815fec 100644
--- a/public/web/WebInputEvent.h
+++ b/public/web/WebInputEvent.h
@@ -247,6 +247,10 @@ 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