code: function Speed (opts) {
      Speed.superclass.constructor.call(this, opts)
  
      this.other = opts.action
      this.speed = opts.speed
  }
docs: @class
  Changes the speed of an action, making it take longer (speed>1)
  or less (speed<1) time.
  Useful to simulate 'slow motion' or 'fast forward' effect.
  @warning This action can't be Sequenceable because it is not an IntervalAction
  
  @memberOf cocos.actions
  @extends cocos.actions.Action
  
  @opt {cocos.actions.Action} action Action to change duration of
  @opt {Float} speed How much to multiply the duration by. Values > 1 increase duration, and < 1 will decrease duration.