[js] Improve NativeRef stub.

Author: pmurias

src/vm/js/nqp-runtime/reprs.js

@@ -1036,6 +1036,7 @@ module.exports.VMException = VMException;
 function NativeRef() {
 }
 NativeRef.prototype.allocate = basic_allocate;
+NativeRef.prototype.create_obj_constructor = basic_constructor;
 NativeRef.prototype.type_object_for = basic_type_object_for;
 NativeRef.prototype.compose = noop_compose;
 module.exports.NativeRef = NativeRef;