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
const capitalizedEvent = event[0].toUpperCase() + event.slice(1);
  const onEvent = 'on' + capitalizedEvent;
  const type = {
    phasedRegistrationNames: {
      bubbled: onEvent,
      captured: onEvent + 'Capture',
    },
    dependencies: [topEvent],
    isInteractive,
  };
  eventTypes[event] = type;
  topLevelEventsToDispatchConfig[topEvent] = type;
}
interactiveEventTypeNames.forEach(eventTuple => {
  addEventTypeNameToConfig(eventTuple, true);
});
nonInteractiveEventTypeNames.forEach(eventTuple => {
  addEventTypeNameToConfig(eventTuple, false);
});
// Only used in DEV for exhaustiveness validation.
const knownHTMLTopLevelTypes: Array<DOMTopLevelEventType> = [
  DOMTopLevelEventTypes.TOP_ABORT,
  DOMTopLevelEventTypes.TOP_CANCEL,
  DOMTopLevelEventTypes.TOP_CAN_PLAY,
  DOMTopLevelEventTypes.TOP_CAN_PLAY_THROUGH,
  DOMTopLevelEventTypes.TOP_CLOSE,
  DOMTopLevelEventTypes.TOP_DURATION_CHANGE,
  DOMTopLevelEventTypes.TOP_EMPTIED,
  DOMTopLevelEventTypes.TOP_ENCRYPTED,
  DOMTopLevelEventTypes.TOP_ENDED,