kiosk-shell: Update view transform after activation.

The activation of a view implies, among other things, a change in the associated view layer which is initially unset. In order for this change to be reflected in the corresponding surface's output mask, and hence allow surface damage to trigger output repaints, we need to update the view transform.

Fixes #674 (closed)

Signed-off-by: Alexandros Frantzis alexandros.frantzis@collabora.com