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:

this._testJournal.stateAtStartOfWillUnmount = clone(this.state);
        this._testJournal.lifeCycleAtStartOfWillUnmount = getLifeCycleState(
          this,
        );
        this.state.hasWillUnmountCompleted = true;
      }
    }
    
    
    
    const container = document.createElement('div');
    let instance;
    expect(() => {
      instance = ReactDOM.render(<LifeCycleComponent />, container);
    }).toWarnDev(
      'LifeCycleComponent is accessing isMounted inside its render() function',
      {withoutStack: true},
    );
    
    expect(instance._testJournal.returnedFromGetInitialState).toEqual(
      GET_INIT_STATE_RETURN_VAL,
    );
    expect(instance._testJournal.lifeCycleAtStartOfGetInitialState).toBe(
      'UNMOUNTED',
    );
    
    expect(instance._testJournal.stateAtStartOfWillMount).toEqual(
      instance._testJournal.returnedFromGetInitialState,
    );