react/prop-types doesn't work when mixing createReactClass with ES6 style prop types

To facilitate moving to ES6 classes we're mixing createReactClass with ES6 style prop types.

react/prop-types doesn't seem to recognize prop types in this case and reports all used props as "missing in props validation".

File to reproduce:

'use strict';

const createReactClass = require('create-react-class');
const React = require('react');
const PropTypes = require('prop-types');

const Component = createReactClass({
  render: function () {
    return (<div>{this.props.prop}</div>);
  }
});

Component.propTypes = {
  prop: PropTypes.string
};

module.exports = Component;

Start by running the inline reproduction with the react/prop-types rule enabled, then trace the rule's handling of createReactClass and the subsequent Component.propTypes assignment. Done means the prop validation warning is no longer reported for the shown prop while existing missing-prop validation still works.