Bug 1023046 - Finetune app to app tranisiton by ordering

This is not readable... considering doing this above Line 179 to overwrite `openAnimation` and `closeAnimation`

    if (immediateTranstion) {
      // animation should alway be immediate.
      openAnimation = 'immediate';
    } else if (switching) {
      // switching animation is decided here and shouldn't be open/closeAnimation
      if (appNext.createdTime > appCurrent.createdTime) {
        ...
      } else {
        ...
      }
    }