Fix PaintedItem redraw bug

Fix PaintedItem redraw bug

1) After QQuickItem::update() being called (means item's content is dirty),
   the paint() function should always been called, so the contentsDirty
   and geometryDirty flags are not needed.
2) Update the smile example to validate the above changes

Task-number:QTBUG-22250
Change-Id: I5a72f18e6982bdb3ba23e78a253c2876aca2e8cb
Reviewed-by: Michael Brasser <michael.brasser@nokia.com>
Reviewed-by: Yoann Lopes <yoann.lopes@nokia.com>