Remove Unused AsTextButtonBorder RTTI helper.

ui/views/border.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/border.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/gfx/canvas.h"
 #include "ui/views/painter.h"
@@ skipping 148 matching lines @@
   return scoped_ptr<Border>(
       new SidedSolidBorder(top, left, bottom, right, color));
 }
 
 // static
 scoped_ptr<Border> Border::CreateBorderPainter(Painter* painter,
                                                const gfx::Insets& insets) {
   return scoped_ptr<Border>(new BorderPainter(painter, insets));
 }
 
-TextButtonBorder* Border::AsTextButtonBorder() {
-  return NULL;
-}
-
-const TextButtonBorder* Border::AsTextButtonBorder() const {
-  return NULL;
-}
-
 }  // namespace views