DevTools: preserve selected sidebar tab when dynamically switching the layout.

Source/devtools/front_end/elements/ElementsPanel.js

 /*
  * Copyright (C) 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2008 Matt Lilek <webkit@mattlilek.com>
  * 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
@@ skipping 949 matching lines @@
             vertically = true;
         else
             vertically = WebInspector.inspectorView.element.offsetWidth < 680;
 
         if (this.sidebarPaneView && vertically === !this._splitWidget.isVertical())
             return;
 
         if (this.sidebarPaneView && this.sidebarPaneView.shouldHideOnDetach())
             return; // We can't reparent extension iframes.
 
+        var selectedTabId = this.sidebarPaneView ? this.sidebarPaneView.selectedTabId : null;
+
         var extensionSidebarPanes = WebInspector.extensionServer.sidebarPanes();
         if (this.sidebarPaneView) {
             this.sidebarPaneView.detach();
             this._splitWidget.uninstallResizer(this.sidebarPaneView.headerElement());
         }
 
         this._splitWidget.setVertical(!vertically);
 
         var computedPane = new WebInspector.SidebarPane(WebInspector.UIString("Computed"));
         computedPane.element.classList.add("composite");
@@ skipping 78 matching lines @@
         for (var sidebarViewWrapper of this._elementsSidebarViewWrappers)
             this.sidebarPaneView.addPane(sidebarViewWrapper);
 
         this._extensionSidebarPanesContainer = this.sidebarPaneView;
 
         for (var i = 0; i < extensionSidebarPanes.length; ++i)
             this._addExtensionSidebarPane(extensionSidebarPanes[i]);
 
         this._splitWidget.setSidebarWidget(this.sidebarPaneView);
         this.sidebarPanes.styles.expand();
+
+        if (selectedTabId)
+            this.sidebarPaneView.selectTab(selectedTabId);
     },
 
     /**
      * @param {!WebInspector.Event} event
      */
     _extensionSidebarPaneAdded: function(event)
     {
         var pane = /** @type {!WebInspector.ExtensionSidebarPane} */ (event.data);
         this._addExtensionSidebarPane(pane);
     },
@@ skipping 268 matching lines @@
         if (enabled)
             return;
 
         var selectedNode = this._treeOutline.selectedDOMNode();
         if (selectedNode)
             WebInspector.DefaultDOMNodeHighlighter.prototype.highlightDOMNode.call(this, selectedNode, config);
     },
 
     __proto__: WebInspector.DefaultDOMNodeHighlighter.prototype
 }