Set item z-order in relation to the backgroundRect.
Set item z-order in relation to the backgroundRect.

Use the backgroundRect as the base instead of the map which may
not always be available.

Change-Id: I502709ce5de45408afc115df10d6bd2302169043
Reviewed-by: Natalia Shubina <2041007149eb9d1657a42550d07ee3dad25a2f4d@nokia.com>
Reviewed-by: abcd <56cdaeb01576a04ff2918a370e5ee13fc1db3bea@nokia.com>
Reviewed-by: Aaron McCarthy <19f0c2781a6d2138802be69a27973bb2f9d34578@nokia.com>

kobolabs/qtlocation,amccarthy/qtlocation,kobolabs/qtlocation,kobolabs/qtlocation,amccarthy/qtlocation,amccarthy/qtlocation