fix(RTC): invalid reference

modules/RTC/RTC.js

             delete this.remoteTracks[
                 toBeRemoved.getParticipantId()][toBeRemoved.getType()];
 
-            this.rtc.eventEmitter.emit(
+            this.eventEmitter.emit(
                 RTCEvents.REMOTE_TRACK_REMOVED, toBeRemoved);
         }