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:

expect(instance._testJournal.lifeCycleAtStartOfWillMount).toBe('UNMOUNTED');
    
    expect(instance._testJournal.stateAtStartOfDidMount).toEqual(
      DID_MOUNT_STATE,
    );
    expect(instance._testJournal.lifeCycleAtStartOfDidMount).toBe('MOUNTED');
    
    expect(instance._testJournal.stateInInitialRender).toEqual(
      INIT_RENDER_STATE,
    );
    expect(instance._testJournal.lifeCycleInInitialRender).toBe('UNMOUNTED');
    expect(getLifeCycleState(instance)).toBe('MOUNTED');
    
    instance.forceUpdate();
    
    expect(instance._testJournal.stateInLaterRender).toEqual(NEXT_RENDER_STATE);
    expect(instance._testJournal.lifeCycleInLaterRender).toBe('MOUNTED');
    expect(getLifeCycleState(instance)).toBe('MOUNTED');
    ReactDOM.unmountComponentAtNode(container);
    expect(instance._testJournal.stateAtStartOfWillUnmount).toEqual(
      WILL_UNMOUNT_STATE,
    );
    
    expect(instance._testJournal.lifeCycleAtStartOfWillUnmount).toBe('MOUNTED');
    
    expect(getLifeCycleState(instance)).toBe('UNMOUNTED');
    expect(instance.state).toEqual(POST_WILL_UNMOUNT_STATE);
  });
  it('should not throw when updating an auxiliary component', () => {
    class Tooltip extends React.Component {