http://stackoverflow.com/a/29610781
There is an alternative solution on fixing this issue which is found here. Try to check the score on PageSpeed Insights by changing the Google-Analytics from:
http://www.google-analytics.com/analytics.js to this URL:
http://www.schedule-analytics.com/analytics.js
EDIT/UPDATE:
Please consider this method as an alternative solution or just a reference to show that it is work to get PageSpeed Insights 100/100 and solve the 99/100 issue. Despite it is worked for me I must agree that the .js link is apparently not reliable. I've created a topic to get an advise on the project discussion. Seems the uptime is now fixed. However, I would recommend the best way is put a copy of analytics.js on your own server and implement the same method that explained it is referring to this article.