According to spec version below, http://www.w3.org/TR/2013/WD-notifications-20130912/ add 5 readonly attributes in Notification.idl.
Created attachment 241931 [details] Patch
Created attachment 241952 [details] Patch
Comment on attachment 241952 [details] Patch Hi, Apologies that your patch was not reviewed in a timely manner. Since it's now quite old, I am removing it from the review request queue. Please consider rebasing it on trunk and resubmitting. To increase the chances of getting a review, consider using 'Tools/Scripts/webkit-patch upload --suggest-reviewers' to CC reviewers who might be interested in this bug.