We're switching Atom to React, but we want to support backward-compatible shims to our previous view framework.

In the old framework, views were represented as jQuery-wrapped DOM elements. Ideally, we'd like to provide backward-compatible shims by simply rendering the React component and wrapping its root element in a jQuery wrapper with an API that's compatible to our old editor views. That would essentially look like this:

``` javascript
var editorRoot = document.createElement('div')
React.renderComponentWithRootElement(Editor(props), editorRoot)

// the element would actually be wrapped in a custom subclass of jQuery,
// but this is clearer for this example
var editorShim = $(editorRoot) 
```

Currently, this isn't possible because React components need to be rendered into a container. So instead we need to create a wrapper element and render the component inside it. This is sad because it adds an extra layer of markup which confuses styling, and also means that the editor has a wrapper when used via the shim layer but no wrapper when embedded as a child via React itself.

Is there something fundamental preventing React from adopting DOM nodes directly without the parent? Is this something we could even hack in in a way that would be somewhat maintainable?

:heart:

log.push('render');
        instance = this;
        return null;
      }
    }
    const shallowRenderer = createRenderer();
    shallowRenderer.render(<Component />);
    log.length = 0;
    instance.setState(() => null);
    instance.setState(() => undefined);
    instance.setState(null);
    instance.setState(undefined);
    expect(log).toEqual([]);
    instance.setState(state => ({count: state.count + 1}));
    expect(log).toEqual(['render']);
  });
  it('should not get this in a function component', () => {
    const logs = [];
    function Foo() {
      logs.push(this);
      return <div>foo</div>;
    }
    const shallowRenderer = createRenderer();
    shallowRenderer.render(<Foo foo="bar" />);
    expect(logs).toEqual([undefined]);
  });
});