fix(toolbox): Show dominant speaker name only when in conference

react/features/conference/components/web/Conference.js

                         <Filmstrip />
                     </div>
 
-                    { _showPrejoin || _showLobby || <Toolbox /> }
+                    { _showPrejoin || _showLobby || <Toolbox showDominantSpeakerName = { true } /> }
                     <Chat />
 
                     { this.renderNotificationsContainer() }

react/features/toolbox/components/web/Toolbox.js

      */
     dispatch: Function,
 
+    /**
+     * If the dominant speaker name should be displayed or not.
+     */
+    showDominantSpeakerName?: boolean,
+
     /**
      * Invoked to obtain translated strings.
      */
      * Explicitly passed array with the buttons which this Toolbox should display.
      */
     toolbarButtons: Array<string>,
+
 };
 
 declare var APP: Object;
             _isMobile,
             _overflowMenuVisible,
             _toolbarButtons,
+            showDominantSpeakerName,
             t,
             _reactionsEnabled
         } = this.props;
                         onMouseOut: this._onMouseOut,
                         onMouseOver: this._onMouseOver
                     }) }>
-                    <DominantSpeakerName />
+
+                    { showDominantSpeakerName && <DominantSpeakerName /> }
+
                     <div className = 'toolbox-content-items'>
                         {mainMenuButtons.map(({ Content, key, ...rest }) => Content !== Separator && (
                             <Content