make sure we polishItems also in plain render loop

Change-Id: Ife8ab271c77a8daeaca9463e72296714aba17df9
Reviewed-on: http://codereview.qt-project.org/4430


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>