add 'slow' prefix to RenderObject's firstChild() / lastChild() methods

Source/core/rendering/FixedTableLayout.cpp

 /*
  * Copyright (C) 2002 Lars Knoll (knoll@kde.org)
  *           (C) 2002 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc.
  *
  * 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.
  *
@@ skipping 119 matching lines @@
         }
     }
 
     // Iterate over the first row in case some are unspecified.
     RenderTableSection* section = m_table->topNonEmptySection();
     if (!section)
         return usedWidth;
 
     unsigned currentColumn = 0;
 
-    RenderObject* firstRow = section->firstChild();
+    RenderTableRow* firstRow = toRenderTableRow(section->firstChild());
     for (RenderObject* child = firstRow->firstChild(); child; child = child->nextSibling()) {
         if (!child->isTableCell())
             continue;
 
         RenderTableCell* cell = toRenderTableCell(child);
 
         Length logicalWidth = cell->styleOrColLogicalWidth();
         unsigned span = cell->colSpan();
         int fixedBorderBoxLogicalWidth = 0;
         // FIXME: Support other length types. If the width is non-auto, it should probably just use
@@ skipping 182 matching lines @@
             for (RenderObject* cell = row->firstChild(); cell; cell = cell->nextSibling()) {
                 if (!cell->isTableCell())
                     continue;
                 cell->setPreferredLogicalWidthsDirty();
             }
         }
     }
 }
 
 } // namespace WebCore