[DevTools] Rework some focus code.

third_party/WebKit/Source/devtools/front_end/elements/ElementsTreeOutline.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 141 matching lines @@
     focus: function()
     {
         this._element.focus();
     },
 
     /**
      * @return {boolean}
      */
     hasFocus: function()
     {
-        return this._element === WebInspector.currentFocusElement();
+        return this._element.hasFocus();
     },
 
     /**
      * @param {boolean} wrap
      */
     setWordWrap: function(wrap)
     {
         this._element.classList.toggle("elements-tree-nowrap", !wrap);
     },
 
@@ skipping 1624 matching lines @@
             if (node) {
                 this.treeOutline._selectedDOMNode = node;
                 this.treeOutline._selectedNodeChanged();
             }
         }
         return true;
     },
 
     __proto__: TreeElement.prototype
 }