DevTools: Disable timeline network pane resizer when network group is collapsed.

third_party/WebKit/Source/devtools/front_end/ui/SplitWidget.js

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  * 1. Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *
@@ skipping 720 matching lines @@
       this._savedHorizontalMainSize = this._totalSizeDIP() - this._sidebarSizeDIP;
   }
 
   /**
    * @param {!Common.Event} event
    */
   _onResizeEnd(event) {
     this._resizeStartSizeDIP = 0;
   }
 
-  hideDefaultResizer() {
+  /**
+   * @param {boolean=} noSplitter
+   */
+  hideDefaultResizer(noSplitter) {
     this.uninstallResizer(this._resizerElement);
+    this._sidebarElement.classList.toggle('no-default-splitter', noSplitter);
   }
 
   /**
    * @param {!Element} resizerElement
    */
   installResizer(resizerElement) {
     this._resizerWidget.addElement(resizerElement);
   }
 
   /**
@@ skipping 156 matching lines @@
   OnlySidebar: 'OnlySidebar'
 };
 
 /** @enum {symbol} */
 UI.SplitWidget.Events = {
   SidebarSizeChanged: Symbol('SidebarSizeChanged'),
   ShowModeChanged: Symbol('ShowModeChanged')
 };
 
 UI.SplitWidget.MinPadding = 20;