Apply FINAL to the RenderObject hierarchy.

Source/core/rendering/RenderTextControlMultiLine.h

 /*
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/) 
  * Copyright (C) 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.
  *
  * 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.
  *
  */
 
 #ifndef RenderTextControlMultiLine_h
 #define RenderTextControlMultiLine_h
 
 #include "RenderTextControl.h"
 
 namespace WebCore {
 
-class RenderTextControlMultiLine : public RenderTextControl {
+class RenderTextControlMultiLine FINAL : public RenderTextControl {
 public:
     RenderTextControlMultiLine(Element*);
     virtual ~RenderTextControlMultiLine();
 
 private:
     virtual bool isTextArea() const { return true; }
 
     virtual bool nodeAtPoint(const HitTestRequest&, HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction) OVERRIDE;
 
     virtual float getAvgCharWidth(AtomicString family);
@@ skipping 11 matching lines @@
     ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isTextArea());
     return static_cast<RenderTextControlMultiLine*>(object);
 }
 
 // This will catch anyone doing an unnecessary cast.
 void toRenderTextControlMultiLine(const RenderTextControlMultiLine*);
 
 }
 
 #endif