[Devtools] Change logic of DataGrid's padding-left for grouping

third_party/WebKit/Source/devtools/front_end/data_grid/ViewportDataGrid.js

 // Copyright 2014 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.
 /**
  * @unrestricted
  * @extends {DataGrid.DataGrid<!NODE_TYPE>}
  * @template NODE_TYPE
  */
 DataGrid.ViewportDataGrid = class extends DataGrid.DataGrid {
   /**
@@ skipping 444 matching lines @@
       return;
     this.clearFlatNodes();
     super.expand();
     this.dataGrid.scheduleUpdateStructure();
   }
 
   /**
    * @protected
    */
   willAttach() {
+    var leftPadding = this.leftPadding;
+    var disclosureCell = this.disclosureCell();
+    if (leftPadding && disclosureCell)
+      disclosureCell.style.setProperty('padding-left', leftPadding + 'px');
   }
 
   /**
    * @protected
    * @return {boolean}
    */
   attached() {
     return !!(this.dataGrid && this.existingElement() && this.existingElement().parentElement);
   }
 
@@ skipping 29 matching lines @@
 
   /**
    * @override
    * @param {number} index
    */
   recalculateSiblings(index) {
     this.clearFlatNodes();
     super.recalculateSiblings(index);
   }
 };