Method is_root_script

modules/gdscript/gdscript.h:265–265

	bool has_class(const GDScript *p_script);
	GDScript *get_root_script();
	bool is_root_script() const { return _owner == nullptr; }
	String get_fully_qualified_name() const { return fully_qualified_name; }
	const HashMap<StringName, Ref<GDScript>> &get_subclasses() const { return subclasses; }
	const HashMap<StringName, Variant> &get_constants() const { return constants; }