listitemfactory: Track notify manually instead of freeze/thaw
freeze/thaw_notify () showed up on the perf trace for rapid ColumnView scrolling. Track the three properties manually to make it a little faster (although the main bulk is still on the g_object_notify ()
).
Related: #3334 (closed)
I guess this by extension also adds delayed notification to other callers of gtk_list_item_widget_default_update ()
which didn't freeze/thaw.
cc @otte