feat(es) migrate statistics/statistics to ES6 Class

Author: naman9271

JitsiConference.js

@@ -901,16 +901,6 @@ JitsiConference.prototype.getLocalVideoTracks = function() {
     return this.rtc ? this.rtc.getLocalVideoTracks() : null;
 };
 
-/**
- * Obtains the performance statistics.
- * @returns {Object|null}
- */
-JitsiConference.prototype.getPerformanceStats = function() {
-    return {
-        longTasksStats: this.statistics.getLongTasksStats()
-    };
-};
-
 /**
  * Attaches a handler for events(For example - "participant joined".) in the
  * conference. All possible event are defined in JitsiConferenceEvents.
@@ -3907,8 +3897,7 @@ JitsiConference.prototype._sendConferenceLeftAnalyticsEvent = function() {
         meetingId,
         participantId: `${meetingId}.${this._statsCurrentId}`,
         stats: {
-            duration: Math.floor((Date.now() - this._conferenceJoinAnalyticsEventSent) / 1000),
-            perf: this.getPerformanceStats()
+            duration: Math.floor((Date.now() - this._conferenceJoinAnalyticsEventSent) / 1000)
         }
     }));
 };