Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/css/StyleSheetList.cpp

 /**
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007 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 24 matching lines @@
     : m_treeScope(treeScope)
 {
 }
 
 StyleSheetList::~StyleSheetList()
 {
 }
 
 inline const WillBeHeapVector<RefPtrWillBeMember<StyleSheet> >& StyleSheetList::styleSheets()
 {
+#if !ENABLE(OILPAN)
     if (!m_treeScope)
         return m_detachedStyleSheets;
+#endif
     return document()->styleEngine()->styleSheetsForStyleSheetList(*m_treeScope);
 }
 
+#if !ENABLE(OILPAN)
 void StyleSheetList::detachFromDocument()
 {
-    // FIXME: Oilpan: This is safe currently because the Document is
-    // *not* in the oilpan heap and the style engine is alive when the
-    // document dies. When the Document is in the oilpan heap, we need
-    // the StyleSheetList and the document to die together and get rid
-    // of the detachedStyleSheets.
     m_detachedStyleSheets = document()->styleEngine()->styleSheetsForStyleSheetList(*m_treeScope);
-    m_treeScope = 0;
+    m_treeScope = nullptr;
 }
+#endif
 
 unsigned StyleSheetList::length()
 {
     return styleSheets().size();
 }
 
 StyleSheet* StyleSheetList::item(unsigned index)
 {
     const WillBeHeapVector<RefPtrWillBeMember<StyleSheet> >& sheets = styleSheets();
     return index < sheets.size() ? sheets[index].get() : 0;
 }
 
 HTMLStyleElement* StyleSheetList::getNamedItem(const AtomicString& name) const
 {
+#if !ENABLE(OILPAN)
     if (!m_treeScope)
         return 0;
+#endif
 
     // IE also supports retrieving a stylesheet by name, using the name/id of the <style> tag
     // (this is consistent with all the other collections)
     // ### Bad implementation because returns a single element (are IDs always unique?)
     // and doesn't look for name attribute.
     // But unicity of stylesheet ids is good practice anyway ;)
     // FIXME: We should figure out if we should change this or fix the spec.
     Element* element = m_treeScope->getElementById(name);
     return isHTMLStyleElement(element) ? toHTMLStyleElement(element) : 0;
 }
 
 CSSStyleSheet* StyleSheetList::anonymousNamedGetter(const AtomicString& name)
 {
     HTMLStyleElement* item = getNamedItem(name);
     if (!item)
         return 0;
     return item->sheet();
 }
 
 void StyleSheetList::trace(Visitor* visitor)
 {
-    visitor->trace(m_detachedStyleSheets);
+    visitor->trace(m_treeScope);
 }
 
 } // namespace WebCore