
This reverts commit 35d92e0faca5f8faaf1393e467d8ddb43c84db92. This turned out to cause trouble, because it can prevent MetaWaylandSurface::applied_state.subsurface_branch_node from ever getting linked up for a sub-surface. It shouldn't be necessary anyway, since permanently_unmap_subsurface / wl_subcompositor_get_subsurface reset the sub-surface state as defined by the protocol. Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3737>