cssnode: Make widget node not copy the path
cssnode: Make widget node not copy the path

Instead, use gtk_widget_get_path() which makes GtkWidget cache the path.
This is a temporary solution until we can get rid of widget paths.

This increases memory usage quite noticably.

chergert/gtk,grubersjoe/adwaita,jigpu/gtk,grubersjoe/adwaita,alexlarsson/gtk,alexlarsson/gtk,Lyude/gtk-,davidgumberg/gtk,Adamovskiy/gtk,Adamovskiy/gtk,jadahl/gtk,davidgumberg/gtk,grubersjoe/adwaita,alexlarsson/gtk,jadahl/gtk,jadahl/gtk,davidgumberg/gtk,jigpu/gtk,chergert/gtk,grubersjoe/adwaita,grubersjoe/adwaita,Lyude/gtk-,davidgumberg/gtk,Adamovskiy/gtk,Lyude/gtk-,alexlarsson/gtk,ahodesuka/gtk,jadahl/gtk,jigpu/gtk,davidgumberg/gtk,chergert/gtk,ahodesuka/gtk,chergert/gtk,jadahl/gtk,Adamovskiy/gtk,grubersjoe/adwaita,ahodesuka/gtk,davidgumberg/gtk,davidgumberg/gtk,ahodesuka/gtk,jigpu/gtk,chergert/gtk,ahodesuka/gtk,jigpu/gtk,chergert/gtk,Adamovskiy/gtk,chergert/gtk,jadahl/gtk,Adamovskiy/gtk,Lyude/gtk-,alexlarsson/gtk,chergert/gtk,jigpu/gtk,ahodesuka/gtk,Adamovskiy/gtk,jigpu/gtk,alexlarsson/gtk,Lyude/gtk-,Adamovskiy/gtk,jadahl/gtk,jadahl/gtk,alexlarsson/gtk,alexlarsson/gtk,davidgumberg/gtk,ahodesuka/gtk,grubersjoe/adwaita,grubersjoe/adwaita,Lyude/gtk-,ahodesuka/gtk,Lyude/gtk-,Lyude/gtk-,jigpu/gtk