DevTools: Make labeled checkbox a web component

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 702 matching lines @@
     {
         var treeOutline = this._treeOutlineForNode(node);
         return /** @type {?WebInspector.ElementsTreeElement} */ (treeOutline.findTreeElement(node));
     },
 
     /**
      * @param {!Event} event
      */
     handleCopyEvent: function(event)
     {
-        if (!WebInspector.currentFocusElement().enclosingNodeOrSelfWithClass("elements-tree-outline"))
+        if (!WebInspector.currentFocusElement() || !WebInspector.currentFocusElement().enclosingNodeOrSelfWithClass("elements-tree-outline"))
             return;
         var treeOutline = this._treeOutlineForNode(this.selectedDOMNode());
         if (treeOutline)
             treeOutline.handleCopyOrCutKeyboardEvent(false, event);
     },
 
     /**
      * @param {!Event} event
      */
     handleCutEvent: function(event)
@@ skipping 341 matching lines @@
 WebInspector.ElementsPanelFactory.prototype = {
     /**
      * @override
      * @return {!WebInspector.Panel}
      */
     createPanel: function()
     {
         return WebInspector.ElementsPanel.instance();
     }
 }