Minor improvement to jitter measurement

Frontend/speedtest_worker.js

@@ -457,7 +457,9 @@ function pingTest (done) {
         var instjitter = Math.abs(instspd - prevInstspd)
         if (i === 1) ping = instspd; /* first ping, can't tell jitter yet*/ else {
           ping = instspd < ping ? instspd : ping * 0.8 + instspd * 0.2 // update ping, weighted average. if the instant ping is lower than the current average, it is set to that value instead of averaging
-          jitter = instjitter > jitter ? (jitter * 0.3 + instjitter * 0.7) : (jitter * 0.8 + instjitter * 0.2) // update jitter, weighted average. spikes in ping values are given more weight.
+          if(i === 2) jitter=instjitter //discard the first jitter measurement because it might be much higher than it should be
+			else 
+		  jitter = instjitter > jitter ? (jitter * 0.3 + instjitter * 0.7) : (jitter * 0.8 + instjitter * 0.2) // update jitter, weighted average. spikes in ping values are given more weight.
         }
         prevInstspd = instspd
       }