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

Source/core/xml/XPathExpressionNode.h

 /*
  * Copyright (C) 2005 Frerich Raabe <raabe@kde.org>
  * Copyright (C) 2006, 2009 Apple Inc.
  *
  * 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.
@@ skipping 42 matching lines @@
 class ParseNode : public GarbageCollectedFinalized<ParseNode> {
 public:
     virtual ~ParseNode() { }
     DEFINE_INLINE_VIRTUAL_TRACE() { }
 };
 
 class Expression : public ParseNode {
     WTF_MAKE_NONCOPYABLE(Expression);
 public:
     Expression();
-    virtual ~Expression();
+    ~Expression() override;
     DECLARE_VIRTUAL_TRACE();
 
     virtual Value evaluate(EvaluationContext&) const = 0;
 
     void addSubExpression(Expression* expr)
     {
         m_isContextNodeSensitive |= expr->m_isContextNodeSensitive;
         m_isContextPositionSensitive |= expr->m_isContextPositionSensitive;
         m_isContextSizeSensitive |= expr->m_isContextSizeSensitive;
         m_subExpressions.append(expr);
@@ skipping 20 matching lines @@
     bool m_isContextNodeSensitive;
     bool m_isContextPositionSensitive;
     bool m_isContextSizeSensitive;
 };
 
 } // namespace XPath
 
 } // namespace blink
 
 #endif // XPathExpressionNode_h