ref(SmallVideo): add 'isCurrentlyOnLargeVideo'

modules/UI/videolayout/LocalVideo.js

         localVideoContainer.removeChild(localVideo);
         // when removing only the video element and we are on stage
         // update the stage
-        if(this.VideoLayout.isCurrentlyOnLarge(this.id))
+        if(this.isCurrentlyOnLargeVideo())
             this.VideoLayout.updateLargeVideo(this.id);
         stream.off(TrackEvents.LOCAL_TRACK_STOPPED, endedHandler);
     };

modules/UI/videolayout/RemoteVideo.js

 
     // when removing only the video element and we are on stage
     // update the stage
-    if (isVideo && this.VideoLayout.isCurrentlyOnLarge(this.id))
+    if (isVideo && this.isCurrentlyOnLargeVideo())
         this.VideoLayout.updateLargeVideo(this.id);
 };
 

modules/UI/videolayout/SmallVideo.js

     return this.selectVideoElement().length !== 0;
 };
 
+/**
+ * Checks whether the user associated with this <tt>SmallVideo</tt> is currently
+ * being displayed on the "large video".
+ *
+ * @return {boolean} <tt>true</tt> if the user is displayed on the large video
+ * or <tt>false</tt> otherwise.
+ */
+SmallVideo.prototype.isCurrentlyOnLargeVideo = function () {
+    return this.VideoLayout.isCurrentlyOnLarge(this.id);
+};
+
 /**
  * Hides or shows the user's avatar.
  * This update assumes that large video had been updated and we will
 
     let avatar = this.$avatar;
 
-    var isCurrentlyOnLarge = this.VideoLayout.isCurrentlyOnLarge(this.id);
+    var isCurrentlyOnLarge = this.isCurrentlyOnLargeVideo();
 
     var showVideo = !this.isVideoMuted && !isCurrentlyOnLarge;
     var showAvatar;