afterLeaveCallback = function () {
    if (called) {
      return
    }

    called = true

    if (callback) {
      callback.apply(null, arguments)
    }
  }
Bind after-leave event for vue instance. Make sure after-leave is called in any browsers.

@param {Vue} instance Vue instance.
@param {Function} callback callback of after-leave event
@param {Number} speed the speed of transition, default value is 300ms
@param {Boolean} once weather bind after-leave once. default value is false.