A test for dependant async script loading performance (see https://www.igvita.com/2014/05/20/script-injected-async-scripts-considered-harmful/)

script-async.js

var head = document.getElementsByTagName('head')[0];

var script_1 = document.createElement('script');
script_1.src = "http://udacity-crp.herokuapp.com/time.js?rtt=1&a";
head.appendChild(script_1);

var script_2 = document.createElement('script');
script_2.src = "http://udacity-crp.herokuapp.com/time.js?rtt=1&b";
head.appendChild(script_2);