Function prefixKey

docs/external/js/react-dom.development.js:4504–4506

* @param {string} prefix vendor-specific prefix, eg: Webkit * @param {string} key style name, eg: transitionDuration * @return {string} style name prefixed with `prefix`, properly camelCased, eg: * WebkitTransitionDuration

(prefix, key)

   */

  function prefixKey(prefix, key) {
    return prefix + key.charAt(0).toUpperCase() + key.substring(1);
  }
  /**
   * Support style names that may come passed in prefixed by adding permutations
   * of vendor prefixes.