We should be able to look at see if the child has a data-react-id attribute but isn't rendered by this copy of React and consequently warn.

See https://groups.google.com/forum/#!topic/reactjs/mdwfKKJ0L2Q.

/**
 * Copyright 2013-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule ReactMount
 */
'use strict';
var DOMLazyTree = require('DOMLazyTree');
var DOMProperty = require('DOMProperty');
var React = require('React');
var ReactBrowserEventEmitter = require('ReactBrowserEventEmitter');