Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/dom/ProcessingInstruction.cpp

Index: Source/core/dom/ProcessingInstruction.cpp
diff --git a/Source/core/dom/ProcessingInstruction.cpp b/Source/core/dom/ProcessingInstruction.cpp
index f5209b6ecc73df43a9e440b05a813df09dd5e59b..16e2b6423ef25794928b1f32ddfbb60171b9cb0e 100644
--- a/Source/core/dom/ProcessingInstruction.cpp
+++ b/Source/core/dom/ProcessingInstruction.cpp
@@ -58,8 +58,10 @@ 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