text: {
    if (isUndef(oldVnode.data.on) && isUndef(vnode.data.on)) {
      return;
    }
  
    var on = vnode.data.on || {};
    var oldOn = oldVnode.data.on || {};
    target$1 = vnode.elm;
    normalizeEvents(on);
    updateListeners(on, oldOn, add$1, remove$2, vnode.context);
  }
  