Class XFourth

test/WebCell.spec.tsx:80–90

        interface XFourth extends WebCell<XFourthProps> {}

        @component({ tagName: 'x-fourth' })
        @observer
        class XFourth extends HTMLElement implements WebCell<XFourthProps> {
            @attribute
            @observable
            accessor name: string | undefined;

            render() {
                return <h2>{this.name}</h2>;
            }
        }
        renderer.render(<XFourth />);

        const tag = document.body.lastElementChild as XFourth;