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:

/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow
 */
import React from 'react';
import {isForwardRef} from 'react-is';
import describeComponentFrame from 'shared/describeComponentFrame';
import getComponentName from 'shared/getComponentName';
import shallowEqual from 'shared/shallowEqual';
import invariant from 'shared/invariant';
import checkPropTypes from 'prop-types/checkPropTypes';
import ReactSharedInternals from 'shared/ReactSharedInternals';
import {enableHooks} from 'shared/ReactFeatureFlags';
import warning from 'shared/warning';
import is from 'shared/objectIs';
import typeof {Dispatcher as DispatcherType} from 'react-reconciler/src/ReactFiberDispatcher';
import type {ReactContext} from 'shared/ReactTypes';