Adds missing require.

JitsiConnection.js

 var XMPP = require("./modules/xmpp/xmpp");
 var JitsiConnectionEvents = require("./JitsiConnectionEvents");
 var JitsiConnectionErrors = require("./JitsiConnectionErrors");
+var Statistics = require("./modules/statistics/statistics");
 
 /**
  * Creates new connection object for the Jitsi Meet server side video conferencing service. Provides access to the

modules/RTC/JitsiRemoteTrack.js

 var JitsiTrack = require("./JitsiTrack");
 var JitsiTrackEvents = require("../../JitsiTrackEvents");
 var RTCBrowserType = require("./RTCBrowserType");
+var Statistics = require("../statistics/statistics");
 
 var ttfmTrackerAudioAttached = false;
 var ttfmTrackerVideoAttached = false;