incorrect mock implementation for Notification.requestPermission

[xiangwangfeng]

your implementation

Notification.requestPermission = function(callback) {
    if (typeof callback === 'function') {
        callback();
        return true
    } else {
        return true
    }
};

while I think the following codes should be more suitable for real environment

Notification.requestPermission = function(callback) {
    if (typeof callback === 'function') {
        callback('granted');
    } 
};

[0xWDG]

> Notification.requestPermission()
< "granted" = $1
> Notification.requestPermission(function (e){console.log(e)})
[Log] granted