Do not make a subclass of Text only to disable selection.

Source/core/dom/Text.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 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.
  *
@@ skipping 32 matching lines @@
     PassRefPtr<Node> mergeNextSiblingNodesIfPossible();
     PassRefPtr<Text> splitText(unsigned offset, ExceptionState&);
 
     // DOM Level 3: http://www.w3.org/TR/DOM-Level-3-Core/core.html#ID-1312295772
 
     String wholeText() const;
     PassRefPtr<Text> replaceWholeText(const String&);
 
     void recalcTextStyle(StyleRecalcChange, Text* nextTextSibling);
     bool textRendererIsNeeded(const NodeRenderingContext&);
-    virtual RenderText* createTextRenderer(RenderStyle*);
+    RenderText* createTextRenderer(RenderStyle*);
     void updateTextRenderer(unsigned offsetOfReplacedData, unsigned lengthOfReplacedData, RecalcStyleBehavior = DoNotRecalcStyle);
 
     virtual void attach(const AttachContext& = AttachContext()) OVERRIDE FINAL;
 
     virtual bool canContainRangeEndPoint() const OVERRIDE FINAL { return true; }
     virtual NodeType nodeType() const OVERRIDE;
 
 protected:
     Text(TreeScope& treeScope, const String& data, ConstructionType type)
         : CharacterData(treeScope, data, type)
@@ skipping 13 matching lines @@
 #ifndef NDEBUG
     virtual void formatForDebugger(char* buffer, unsigned length) const;
 #endif
 };
 
 DEFINE_NODE_TYPE_CASTS(Text, isTextNode());
 
 } // namespace WebCore
 
 #endif // Text_h