React.js should only export the isomorphic stuff. No dependencies on DOM. The secret export stuff is only for the browserify package so we should just do a special case file here:

https://github.com/facebook/react/blob/master/grunt/config/browserify.js#L66

Rename `React.js` -> `ReactBrowserify.js` and `ReactIsomorphic.js` -> `React.js`.

That way we don't take on the dom dependencies in the npm package. Will help with React Native unification.

* This module exists purely in the open source project, and is meant as a way
 * to create a separate standalone build of React. This build has "addons", or
 * functionality we've built and think might be useful but doesn't have a good
 * place to live inside React core.
 */
'use strict';
var LinkedStateMixin = require('LinkedStateMixin');
var React = require('React');
var ReactComponentWithPureRenderMixin =
  require('ReactComponentWithPureRenderMixin');
var ReactCSSTransitionGroup = require('ReactCSSTransitionGroup');
var ReactFragment = require('ReactFragment');
var ReactTransitionGroup = require('ReactTransitionGroup');
var shallowCompare = require('shallowCompare');
var update = require('update');
React.addons = {
  CSSTransitionGroup: ReactCSSTransitionGroup,
  LinkedStateMixin: LinkedStateMixin,
  PureRenderMixin: ReactComponentWithPureRenderMixin,
  TransitionGroup: ReactTransitionGroup,
  createFragment: ReactFragment.create,
  shallowCompare: shallowCompare,
  update: update,
};
if (__DEV__) {
  React.addons.Perf = require('ReactDefaultPerf');
  React.addons.TestUtils = require('ReactTestUtils');
}
module.exports = React;