st-theme-node.c already handles those by itself. Part of https://gitlab.gnome.org/GNOME/gnome-shell/issues/1934
This is all of the original libcroco, minus these two which we don't use: - cr-sel-eng - the CSS selection engine for xmlNode. - cr-style. Part of https://gitlab.gnome.org/GNOME/gnome-shell/issues/1934