解决了无法提示允许的询问。

上述的webkitNotifications换成Notification。

可以参考：https://developer.mozilla.org/en-US/docs/Web/API/notification

如下有sample code: 

function notifyMe() {

  // Let's check if the browser supports notifications

  if (!("Notification" in window)) {

    alert("This browser does not support desktop notification");

  }

  // Let's check if the user is okay to get some notification

  else if (Notification.permission === "granted") {

    // If it's okay let's create a notification

    var notification = new Notification("Hi there!");

  }

  // Otherwise, we need to ask the user for permission

  // Note, Chrome does not implement the permission static property

  // So we have to check for NOT 'denied' instead of 'default'

  else if (Notification.permission !== 'denied') {

    Notification.requestPermission(function (permission) {

      // Whatever the user answers, we make sure Chrome stores the information

      if(!('permission' in Notification)) {

        Notification.permission = permission;

      }

      // If the user is okay, let's create a notification

      if (permission === "granted") {

        var notification = new Notification("Hi there!");

      }

    });

  }

  // At last, if the user already denied any notification, and you 

  // want to be respectful there is no need to bother him any more.

}

html: <button onclick="notifyMe();">Notify me</button>