Function constructor

packages/nerv/__tests__/lifecycle.spec.js:33–36

(p, c)

      let doRender
      class Outer extends Component {
        constructor (p, c) {
          super(p, c)
          this.state = { i: 0 }
        }
        componentDidMount () {
          doRender = () => this.setState({ i: this.state.i + 1 })
        }