Register a key callback to handle back key event with W3C permisison popup

Register a key callback to handle back key event with W3C permisison popup

    - This applies to the permission request popup for W3C Geolocation API.

[Issue#]   P130927-03479
[Problem]  A web page underneath pop-up moves to the previous page when user expects the pop-up closed.
[Cause]    The permission request pop-up did not handle the back-key callback.
[Solution] Register the key callback.

[SCMRequest] Depends on https://review.tizendev.org/gerrit/#/c/91228/

Change-Id: Ib987a8b4e5795a434771d1e7ffe26eb0f8149c38