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

**What is the current behavior?**
This addresses a bug in `enzyme`, https://github.com/airbnb/enzyme/issues/1683.

On [this line](https://github.com/facebook/react/blob/master/packages/react-test-renderer/src/ReactShallowRenderer.js#L110) `element.type()` invokes the SFC with `element` as the `this` value. I believe that this is needed for create-react-class components, but that there needs to be a separate branch for SFCs.

**What is the expected behavior?**
`this` inside a strict-mode SFC will be `undefined`, not the element.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
In all of React 0.13, 0.14, 15, and 16, this bug exists.

While the bug ideally will be fixed, I understand that it's highly unlikely that it would be backported to the 14/15 lines - but I can wrap around it if there's a reliable way, in those versions, to distinguish SFCs from create-react-class components (is there?).
state = {
        counter: 0,
      };
      render() {
        instance = this;
        return (
          <button ref="button" onClick={this.onClick}>
            {this.state.counter}
          </button>
        );
      }
    }
    const shallowRenderer = createRenderer();
    let result = shallowRenderer.render(<SimpleComponent defaultCount={1} />);
    expect(result.props.children).toEqual(0);
    instance.setState((state, props) => {
      return {counter: props.defaultCount + 1};
    });
    result = shallowRenderer.getRenderOutput();
    expect(result.props.children).toEqual(2);
  });
  it('can access component instance from setState updater function', done => {
    let instance;
    class SimpleComponent extends React.Component {