[eslint] no-unused-expressions

.eslintrc.js

         'no-self-compare': 2,
         'no-sequences': 2,
         'no-unmodified-loop-condition': 2,
+        'no-unused-expressions': [
+            'error',
+            {
+                'allowShortCircuit': true,
+                'allowTernary': true
+            }
+        ],
         'no-unused-labels': 2,
         'no-useless-call': 2,
         'no-void': 2,

JitsiConference.js

     this.dtmfManager = null;
     this.somebodySupportsDTMF = false;
     this.authEnabled = false;
-    this.authIdentity;
     this.startAudioMuted = false;
     this.startVideoMuted = false;
     this.startMutedPolicy = {audio: false, video: false};

modules/settings/Settings.js

 
 class Settings {
     constructor() {
-        this.userId;
-        this.callStatsUserName;
-
         const localStorage = getLocalStorage();
 
         if (localStorage) {

modules/xmpp/moderator.js

     this.eventEmitter = emitter;
 
     this.connection = this.xmppService.connection;
-    this.focusUserJid;
     // FIXME:
     // Message listener that talks to POPUP window
     function listener(event) {