DevTools: [SSP] force StylesSidebarPane refresh on undo/redo command happens.

Source/devtools/front_end/elements/StylesSidebarPane.js

 /*
  * Copyright (C) 2007 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Joseph Pecoraro
  *
  * 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 119 matching lines @@
     // IE hack.
     if (value.endsWith("\9"))
         return true;
     if (hasUnknownVendorPrefix(value))
         return true;
 
     return false;
 }
 
 WebInspector.StylesSidebarPane.prototype = {
+    onUndoOrRedoHappened: function()
+    {
+        this.setNode(this.node());
+    },
+
     /**
      * @param {!WebInspector.Event} event
      */
     _onAddButtonLongClick: function(event)
     {
         var cssModel = this.cssModel();
         if (!cssModel)
             return;
         var headers = cssModel.styleSheetHeaders().filter(styleSheetResourceHeader);
 
@@ skipping 3082 matching lines @@
 
     /**
      * @override
      * @return {?WebInspector.ToolbarItem}
      */
     item: function()
     {
         return this._button;
     }
 }