Fix virtual/override/final usage in Source/core/html/.

Source/core/html/PluginDocument.cpp

 /*
  * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 46 matching lines @@
         RawDataDocumentParser::trace(visitor);
     }
 
 private:
     PluginDocumentParser(Document* document)
         : RawDataDocumentParser(document)
         , m_embedElement(nullptr)
     {
     }
 
-    virtual void appendBytes(const char*, size_t) override;
+    void appendBytes(const char*, size_t) override;
 
-    virtual void finish() override;
+    void finish() override;
 
     void createDocumentStructure();
 
     PluginView* pluginView() const;
 
     RefPtrWillBeMember<HTMLEmbedElement> m_embedElement;
 };
 
 void PluginDocumentParser::createDocumentStructure()
 {
@@ skipping 105 matching lines @@
     HTMLDocument::detach(context);
 }
 
 DEFINE_TRACE(PluginDocument)
 {
     visitor->trace(m_pluginNode);
     HTMLDocument::trace(visitor);
 }
 
 }