**Do you want to request a *feature* or report a *bug*?**
bug

**What is the current behavior?**
In normal rendering, you can memoize a class-based component: https://jsfiddle.net/586ea3cx/

With the shallow renderer, it seems like you can't: https://jsfiddle.net/odj217Lv/1/

This might be blocking https://github.com/airbnb/enzyme/pull/1914, in which tests are failing with `Cannot call a class as a function`. (it's tough to repro stuff with the shallow renderer)
state = {value: 0};
      static getDerivedStateFromProps(nextProps, prevState) {
        return {...prevState};
      }
      updateState = () => {
        this.setState(state => ({value: state.value + 1}));
      };
      render() {
        return <div>{`value:${this.state.value}`}</div>;
      }
    }
    const shallowRenderer = createRenderer();
    let result = shallowRenderer.render(<SimpleComponent />);
    expect(result).toEqual(<div>value:0</div>);
    let instance = shallowRenderer.getMountedInstance();
    instance.updateState();
    result = shallowRenderer.getRenderOutput();
    expect(result).toEqual(<div>value:1</div>);
  });
  it('should pass previous state to shouldComponentUpdate even with getDerivedStateFromProps', () => {
    class SimpleComponent extends React.Component {
      constructor(props) {
        super(props);
        this.state = {
          value: props.value,
        };
      }
      static getDerivedStateFromProps(nextProps, prevState) {