Make RenderObject::style() return a const object

Source/core/html/HTMLSelectElement.cpp

 /*
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * 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, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
@@ skipping 367 matching lines @@
 bool HTMLSelectElement::shouldShowFocusRingOnMouseFocus() const
 {
     return true;
 }
 
 bool HTMLSelectElement::canSelectAll() const
 {
     return !usesMenuList();
 }
 
-RenderObject* HTMLSelectElement::createRenderer(RenderStyle*)
+RenderObject* HTMLSelectElement::createRenderer(const RenderStyle*)
 {
     if (usesMenuList())
         return new RenderMenuList(this);
     return new RenderListBox(this);
 }
 
 PassRefPtrWillBeRawPtr<HTMLCollection> HTMLSelectElement::selectedOptions()
 {
     updateListItemSelectedStates();
     return ensureCachedCollection<HTMLCollection>(SelectedOptions);
@@ skipping 1376 matching lines @@
     int focusedIndex = activeSelectionEndListIndex();
     if (focusedIndex < 0)
         focusedIndex = firstSelectableListIndex();
     if (focusedIndex < 0)
         return nullptr;
     HTMLElement* focused = listItems()[focusedIndex];
     return isHTMLOptionElement(focused) ? toHTMLOptionElement(focused) : nullptr;
 }
 
 } // namespace