Introduce QGraphicsItem::ItemHasNoContents.
Introduce QGraphicsItem::ItemHasNoContents.

This flag helps optimize the case where an item is used only as a
transformation node in a scene graph, and where the item itself
doesn't paint anything. This is the default for FxItem (the
subclasses that do paint enable the HasContents flag). This lets
Graphics View know whether there's any point in setting up the
world transform, opacity and other things.

Reviewed-by: Lars

pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk