VE-MW fix commit for I4efbae614e

Local changes:
* Call bindHandlers()/unbindHandlers() in activate/deactivate
* Extend onDocumentKeyDown rather than overwriting it

Change-Id: I0739e71781c5140c54512ab421bdcb6d1df5fbbe
(cherry picked from commit 08bebc9b2b8672dcad310ac20e96c05f59168c4a)