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

Source/core/xml/XPathStep.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 75 matching lines @@
         Kind m_kind;
         AtomicString m_data;
         AtomicString m_namespaceURI;
 
         // When possible, we merge some or all predicates with node test for better performance.
         HeapVector<Member<Predicate>> m_mergedPredicates;
     };
 
     Step(Axis, const NodeTest&);
     Step(Axis, const NodeTest&, HeapVector<Member<Predicate>>&);
-    virtual ~Step();
+    ~Step() override;
     DECLARE_VIRTUAL_TRACE();
 
     void optimize();
 
     void evaluate(EvaluationContext&, Node* context, NodeSet&) const;
 
     Axis axis() const { return m_axis; }
     const NodeTest& nodeTest() const { return *m_nodeTest; }
 
 private:
@@ skipping 10 matching lines @@
     HeapVector<Member<Predicate>> m_predicates;
 };
 
 bool optimizeStepPair(Step*, Step*);
 
 } // namespace XPath
 
 } // namespace blink
 
 #endif // XPathStep_h