Version 15.4.1

As starting Chrome 55, there is a new event `auxclick` to handle middle click, and `click` doesn't trigger by middle click anymore
https://developers.google.com/web/updates/2016/10/auxclick
/**
 * Copyright (c) 2013-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow
 */
import type {DOMTopLevelEventType} from 'events/TopLevelEventTypes';
import {
  unsafeCastStringToDOMTopLevelType,
  unsafeCastDOMTopLevelTypeToString,
} from 'events/TopLevelEventTypes';
import getVendorPrefixedEventName from './getVendorPrefixedEventName';
/**
 * To identify top level events in ReactDOM, we use constants defined by this
 * module. This is the only module that uses the unsafe* methods to express
 * that the constants actually correspond to the browser event names. This lets
 * us save some bundle size by avoiding a top level type -> event name map.
 * The rest of ReactDOM code should import top level types from this file.
 */
export const TOP_ABORT = unsafeCastStringToDOMTopLevelType('abort');
export const TOP_ANIMATION_END = unsafeCastStringToDOMTopLevelType(
  getVendorPrefixedEventName('animationend'),
);