Appears to be working in Firefox but at least Chrome & Safari are broken. Should be a really recent regression so very few possible changes to blame...

Easiest repo: the todo list on our homepage.

/**
 * 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.
 *
 * @emails react-core
 */
'use strict';
describe('ReactDOMOption', function() {
  var React;
  var ReactDOM;
  var ReactTestUtils;
  beforeEach(function() {
    React = require('React');
    ReactDOM = require('ReactDOM');
    ReactTestUtils = require('ReactTestUtils');
  });
  it('should flatten children to a string', function() {
    var stub = <option>{1} {'foo'}</option>;
    stub = ReactTestUtils.renderIntoDocument(stub);
    var node = ReactDOM.findDOMNode(stub);
    expect(node.innerHTML).toBe('1 foo');
  });
  it('should ignore invalid children types', function() {
    spyOn(console, 'error');
    var stub = <option>{1} <div /> {2}</option>;
    stub = ReactTestUtils.renderIntoDocument(stub);