Make RenderObject::style() return a const object

Source/core/layout/LayoutTableCol.cpp

 /*
  * Copyright (C) 1997 Martin Jones (mjones@kde.org)
  *           (C) 1997 Torben Weis (weis@kde.org)
  *           (C) 1998 Waldo Bastian (bastian@kde.org)
  *           (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 84 matching lines @@
     RenderBox::insertedIntoTree();
     table()->addColumn(this);
 }
 
 void LayoutTableCol::willBeRemovedFromTree()
 {
     RenderBox::willBeRemovedFromTree();
     table()->removeColumn(this);
 }
 
-bool LayoutTableCol::isChildAllowed(RenderObject* child, RenderStyle* style) const
+bool LayoutTableCol::isChildAllowed(RenderObject* child, const RenderStyle* style) const
 {
     // We cannot use isTableColumn here as style() may return 0.
     return child->isLayoutTableCol() && style->display() == TABLE_COLUMN;
 }
 
 bool LayoutTableCol::canHaveChildren() const
 {
     // Cols cannot have children. This is actually necessary to fix a bug
     // with libraries.uc.edu, which makes a <p> be a table-column.
     return isTableColumnGroup();
@@ skipping 79 matching lines @@
     return style()->borderStart();
 }
 
 const BorderValue& LayoutTableCol::borderAdjoiningCellAfter(const LayoutTableCell* cell) const
 {
     ASSERT_UNUSED(cell, table()->colElement(cell->col() - 1) == this);
     return style()->borderEnd();
 }
 
 }