A Polyfill to fix the differences in WebKit, Blink and Gecko HTML5 Desktop Notifications, also adds a way to add your own Javascript Notifications in case your Browser doesn't support them natively.

html5-notifications.js

/*
Copyright (C) 2013 Hendrik Beskow

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to
deal in the Software without restriction, including without limitation the
rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER 
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
;(function(win, doc, nav) {
	if ( /* Safari 6, Firefox 22 */ !('Notification' in win && 'permission' in win.Notification && 'requestPermission' in win.Notification)) {
		var PERMISSION_DEFAULT = 'default',
		PERMISSION_GRANTED = 'granted',
		PERMISSION_DENIED = 'denied',
		PERMISSION = [PERMISSION_GRANTED, PERMISSION_DEFAULT, PERMISSION_DENIED],
		isString = function(value) {
			return (value && (value).constructor === String);
		},
		isFunction = function(value) {
			return (value && (value).constructor === Function);
		},
		isObject = function(value) {
			return (value && (value).constructor === Object);
		},
		noop = function() {},
		settings = {
			timeout: 5000,
			sticky: false
		};
		/* isIE9p = ('external' in win && 'msIsSiteMode' in win.external); */
		
		function checkPermission() {
			var permission;
			if ( /* Chrome, Firefox < 22 && ff-html5notifications */ !! ('webkitNotifications' in win && 'checkPermission' in win.webkitNotifications)) {
				permission = PERMISSION[win.webkitNotifications.checkPermission()];
			} else if ( /* Firefox Mobile */ 'mozNotification' in nav) {
				permission = PERMISSION_GRANTED;
			} else {
				permission = (localStorage.getItem('notifications') === null) ? PERMISSION_DEFAULT : localStorage.getItem('notifications');
			}
			return permission;
		}

		function requestPermission(callback) {
			var callbackFunction = isFunction(callback) ? callback : noop;
			if ( /* Chrome, Firefox < 22 && ff-html5notifications */ !! ('webkitNotifications' in win && 'requestPermission' in win.webkitNotifications)) {
				win.webkitNotifications.requestPermission(callbackFunction);
			} else {
				if (checkPermission() == PERMISSION_DEFAULT) {
					if (confirm('Do you want to allow ' + doc.domain + ' to display Notifications?')) {
						localStorage.setItem('notifications', PERMISSION_GRANTED);
						Notification.permission = PERMISSION_GRANTED;
					} else {
						localStorage.setItem('notifications', PERMISSION_DENIED);
						Notification.permission = PERMISSION_DENIED;
					}
				}
				callbackFunction();
			}
		}

		function Notification(title, params) {
			var notification;
			if (isString(title) &&
				isObject(params) &&
				checkPermission() == PERMISSION_GRANTED) {
				if ( /* Firefox Mobile */ 'mozNotification' in nav) {
					notification = nav.mozNotification.createNotification(title, params.body, params.icon);
					if (isFunction(params.onclick)) {
						notification.onclick = params.onclick;
					}
					if (isFunction(params.onclose)) {
						notification.onclose = params.onclose;
					}
					notification.show();
				} else if ( /* Chrome, Firefox < 22 && ff-html5notifications */ 'webkitNotifications' in win && 'createNotification' in win.webkitNotifications) {
					notification = win.webkitNotifications.createNotification(params.icon, title, params.body);
					if (isFunction(params.onclick)) {
						notification.onclick = params.onclick;
					}
					if (isFunction(params.onshow)) {
						notification.onshow = params.onshow;
					}
					if (isFunction(params.onerror)) {
						notification.onerror = params.onerror;
					}
					if (isFunction(params.onclose)) {
						notification.onclose = params.onclose;
					}
					notification.show();
				} else {
					// Your custom code goes here
				}
			}
			return notification;
		}

		if (!('Notification' in win)) {
			Notification.requestPermission = requestPermission;
			win.Notification = Notification;
		}

		if ( !! ('webkitNotifications' in win && 'checkPermission' in win.webkitNotifications)) {
			Object.defineProperty(win.Notification, 'permission', {
				get: function() {
					return PERMISSION[win.webkitNotifications.checkPermission()];
				}
			});
		} else {
			Notification.permission = checkPermission();
		}

		if (!('requestPermission' in win.Notification)) {
			win.Notification.requestPermission = requestPermission;
		}
	}
}(this, this.document, this.navigator));