Allow registering "runtime classes"

modules/gdscript/gdscript.cpp

@@ -95,7 +95,7 @@ Variant GDScriptNativeClass::_new() {
 }
 
 Object *GDScriptNativeClass::instantiate() {
-	return ClassDB::instantiate(name);
+	return ClassDB::instantiate_no_placeholders(name);
 }
 
 Variant GDScriptNativeClass::callp(const StringName &p_method, const Variant **p_args, int p_argcount, Callable::CallError &r_error) {