[Devtools] Cleanup DataGrid.js

third_party/WebKit/Source/devtools/front_end/network/NetworkLogViewColumns.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @constructor
  * @param {!WebInspector.NetworkLogView} networkLogView
  * @param {!WebInspector.Setting} networkLogLargeRowsSetting
  */
 WebInspector.NetworkLogViewColumns = function(networkLogView, networkLogLargeRowsSetting)
@@ skipping 568 matching lines @@
         subtitleDiv.createTextChild(subtitle);
         return fragment;
     },
 
     /**
      * @param {!Event} event
      * @return {boolean}
      */
     contextMenu: function(event)
     {
-        if (!this._gridMode || !event.target.isSelfOrDescendant(this._dataGrid.headerTableBody))
+        if (!this._gridMode || !event.target.isSelfOrDescendant(this._dataGrid.headerTableBody()))
             return false;
 
         var columnConfigs = this._columns.filter(columnConfig => columnConfig.hideable);
         var contextMenu = new WebInspector.ContextMenu(event);
         var nonResponseHeaders = columnConfigs.filter(columnConfig => !columnConfig.isResponseHeader);
         for (var columnConfig of nonResponseHeaders)
             contextMenu.appendCheckboxItem(columnConfig.title, this._toggleColumnVisibility.bind(this, columnConfig), columnConfig.visible);
 
         contextMenu.appendSeparator();
 
@@ skipping 231 matching lines @@
             divider.element.classList.toggle("network-frame-divider-selected", false);
     },
 
     _updateRowsSize: function()
     {
         if (Runtime.experiments.isEnabled("canvasNetworkTimeline"))
             return;
         this._timelineGrid.element.classList.toggle("small", !this._networkLogLargeRowsSetting.get());
     }
 }