Oilpan: Ensure that classes with virtual trace methods always have vtables for their left-most base…

Source/core/html/HTMLDocument.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 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 56 matching lines @@
 
     using Document::write;
     using Document::writeln;
     void write(LocalDOMWindow*, const Vector<String>& text, ExceptionState&);
     void writeln(LocalDOMWindow*, const Vector<String>& text, ExceptionState&);
 
     static bool isCaseSensitiveAttribute(const QualifiedName&);
 
     virtual PassRefPtrWillBeRawPtr<Document> cloneDocumentWithoutChildren() OVERRIDE FINAL;
 
+    virtual void trace(Visitor* visitor) OVERRIDE
+    {
+        Document::trace(visitor);
+        ResourceClient::trace(visitor);
+    }
+
 protected:
     HTMLDocument(const DocumentInit&, DocumentClassFlags extendedDocumentClasses = DefaultDocumentClass);
 
 private:
     HTMLBodyElement* htmlBodyElement() const;
 
     const AtomicString& bodyAttributeValue(const QualifiedName&) const;
     void setBodyAttribute(const QualifiedName&, const AtomicString&);
 
     void addItemToMap(HashCountedSet<AtomicString>&, const AtomicString&);
@@ skipping 11 matching lines @@
 inline bool HTMLDocument::hasExtraNamedItem(const AtomicString& name)
 {
     return m_extraNamedItemCounts.contains(name);
 }
 
 DEFINE_DOCUMENT_TYPE_CASTS(HTMLDocument);
 
 } // namespace blink
 
 #endif // HTMLDocument_h