what loads this javascript and from where?

I am debugging the joomla installation script on my pc (using apache and a php IDE).  The url is http://localhost/WebService4QBWC/joomla/installation/index.php.

Was curious what was causing the install script to generate a new http request every 30 seconds while php IDE was in break mode, so I set an XHR Breakpoint in Chrome DevTools for urls that contain 'localhost'.  

I see the following javascript being the cause:

window.setInterval(function() {
    var r;
    try {
        r = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject("Microsoft.XMLHTTP")
    } catch (e) {
    }
    if (r) {
        r.open("GET", "./", true);
        r.send(null)
    }
}, 30000);

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How do I figure out what is causing this javascript to be loaded and executed?