Fixes: runtime warnings when trying to render 0-size icon

Task-number: QTBUG-37035
Change-Id: I014988cdb57a2001685a8d50d79ee103322ed021
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>
Merge remote-tracking branch 'origin/stable' into dev

Change-Id: I5448195955ebadcbac6de7cc34ab8e40bd45ef56