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
import {accumulateTwoPhaseDispatches} from 'events/EventPropagators';
import SyntheticEvent from 'events/SyntheticEvent';
import * as DOMTopLevelEventTypes from './DOMTopLevelEventTypes';
import warningWithoutStack from 'shared/warningWithoutStack';
import SyntheticAnimationEvent from './SyntheticAnimationEvent';
import SyntheticClipboardEvent from './SyntheticClipboardEvent';
import SyntheticFocusEvent from './SyntheticFocusEvent';
import SyntheticKeyboardEvent from './SyntheticKeyboardEvent';
import SyntheticMouseEvent from './SyntheticMouseEvent';
import SyntheticPointerEvent from './SyntheticPointerEvent';
import SyntheticDragEvent from './SyntheticDragEvent';
import SyntheticTouchEvent from './SyntheticTouchEvent';
import SyntheticTransitionEvent from './SyntheticTransitionEvent';
import SyntheticUIEvent from './SyntheticUIEvent';
import SyntheticWheelEvent from './SyntheticWheelEvent';
import getEventCharCode from './getEventCharCode';
/**
 * Turns
 * ['abort', ...]
 * into
 * eventTypes = {
 *   'abort': {
 *     phasedRegistrationNames: {
 *       bubbled: 'onAbort',
 *       captured: 'onAbortCapture',
 *     },
 *     dependencies: [TOP_ABORT],
 *   },
 *   ...
 * };