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.
 *
 * @providesModule DOMPropertyOperations
 */
'use strict';
var DOMProperty = require('DOMProperty');
var ReactDOMInstrumentation = require('ReactDOMInstrumentation');
var ReactPerf = require('ReactPerf');
var quoteAttributeValueForBrowser = require('quoteAttributeValueForBrowser');
var warning = require('warning');
var VALID_ATTRIBUTE_NAME_REGEX = new RegExp(
  '^[' + DOMProperty.ATTRIBUTE_NAME_START_CHAR + '][' + DOMProperty.ATTRIBUTE_NAME_CHAR + ']*$'
);
var illegalAttributeNameCache = {};
var validatedAttributeNameCache = {};
function isAttributeNameSafe(attributeName) {