dispatchInteractiveEvent这个方法最终会到的地方是：

let _interactiveUpdatesImpl = function(fn, a, b) {
  return fn(a, b);
};

这个函数默认是啥都没有做,后面会重新赋值这个函数，debug的时候是这样的:

function interactiveUpdates$1(fn, a, b) {
      if (isBatchingInteractiveUpdates) {
        return fn(a, b);
      } // If there are any pending interactive updates, synchronously flush them.
      // This needs to happen before we read any handlers, because the effect of
      // the previous event may influence which handlers are called during
      // this event.


      if (!isBatchingUpdates && !isRendering && lowestPriorityPendingInteractiveExpirationTime !== NoWork) {
        // Synchronously flush pending interactive updates.
        performWork(lowestPriorityPendingInteractiveExpirationTime, false);
        lowestPriorityPendingInteractiveExpirationTime = NoWork;
      }

      var previousIsBatchingInteractiveUpdates = isBatchingInteractiveUpdates;
      var previousIsBatchingUpdates = isBatchingUpdates;
      isBatchingInteractiveUpdates = true;
      isBatchingUpdates = true;

      try {
        return fn(a, b);
      } finally {
        isBatchingInteractiveUpdates = previousIsBatchingInteractiveUpdates;
        isBatchingUpdates = previousIsBatchingUpdates;

        if (!isBatchingUpdates && !isRendering) {
          performSyncWork();
        }
      }
    }

这个做了啥