Get rid of useless calls to AtomicString::impl()

Source/core/html/HTMLElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 119 matching lines @@
 
     void handleKeypressEvent(KeyboardEvent*);
     bool supportsSpatialNavigationFocus() const;
 };
 
 DEFINE_NODE_TYPE_CASTS(HTMLElement, isHTMLElement());
 
 inline HTMLElement::HTMLElement(const QualifiedName& tagName, Document& document, ConstructionType type = CreateHTMLElement)
     : Element(tagName, &document, type)
 {
-    ASSERT(tagName.localName().impl());
+    ASSERT(!tagName.localName().isNull());
     ScriptWrappable::init(this);
 }
 
 } // namespace WebCore
 
 #endif // HTMLElement_h