Remove unnecessary Document.h includes in .cpp files

Source/core/html/HTMLOptGroupElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #include "config.h"
 #include "core/html/HTMLOptGroupElement.h"
 
 #include "core/HTMLNames.h"
-#include "core/dom/Document.h"
 #include "core/dom/NodeRenderStyle.h"
 #include "core/html/HTMLSelectElement.h"
 #include "wtf/StdLibExtras.h"
 
 namespace WebCore {
 
 using namespace HTMLNames;
 
 inline HTMLOptGroupElement::HTMLOptGroupElement(Document& document)
     : HTMLElement(optgroupTag, document)
@@ skipping 97 matching lines @@
         select->accessKeyAction(false);
 }
 
 bool HTMLOptGroupElement::isDisplayNone() const
 {
     RenderStyle* style = nonRendererStyle();
     return style && style->display() == NONE;
 }
 
 } // namespace