Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/dom/ProcessingInstruction.cpp

 /*
  * Copyright (C) 2000 Peter Kelly (pmk@post.com)
  * Copyright (C) 2006, 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 38 matching lines @@
 }
 
 PassRefPtr<ProcessingInstruction> ProcessingInstruction::create(Document& document, const String& target, const String& data)
 {
     return adoptRef(new ProcessingInstruction(document, target, data));
 }
 
 ProcessingInstruction::~ProcessingInstruction()
 {
     if (m_sheet)
         m_sheet->clearOwnerNode();

[haraken, 2014/04/25 05:21:42]

You can put this in #if !ENABLE(OILPAN) as well (You're doing that in
~StyleElement()).

[haraken, 2014/04/25 05:29:59]

Discussed with tasak@, and it looks like a right fix would be to leave
clearOwnerNode() here and leave clearOwnerNode() in ~StyleElement() as well.

Since the CSSStyleSheet can be held by a JS wrapper and thus outlive the
Elements, we need to clear the back pointer from the CSSStyleSheet to the
Elements when the Elements die. (We can remove clearOwnerNode() when we make
CSSStyleSheet::m_ownerNode a Member.)

[Mads Ager (chromium), 2014/04/25 10:58:25]

Yeah, good point. I restored the clearing in StyleElement. These are
Persistents, so it is safe to clear the pointers and we should because we have
no guarantee that they die together.

 
+#if !ENABLE(OILPAN)
     if (inDocument())
         document().styleEngine()->removeStyleSheetCandidateNode(this);
+#endif
 }
 
 String ProcessingInstruction::nodeName() const
 {
     return m_target;
 }
 
 Node::NodeType ProcessingInstruction::nodeType() const
 {
     return PROCESSING_INSTRUCTION_NODE;
@@ skipping 171 matching lines @@
         m_sheet->clearOwnerNode();
         m_sheet = nullptr;
     }
 
     // If we're in document teardown, then we don't need to do any notification of our sheet's removal.
     if (document().isActive())
         document().removedStyleSheet(removedSheet.get());
 }
 
 } // namespace