Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/dom/TreeScopeAdopter.cpp

Index: Source/core/dom/TreeScopeAdopter.cpp
diff --git a/Source/core/dom/TreeScopeAdopter.cpp b/Source/core/dom/TreeScopeAdopter.cpp
index 109d47ce4c123db51d7e1eae8fc208f3e5e68afc..cd369be6ee5816d9861a79c2670b4d67c43f3e26 100644
--- a/Source/core/dom/TreeScopeAdopter.cpp
+++ b/Source/core/dom/TreeScopeAdopter.cpp
@@ -38,7 +38,9 @@ void TreeScopeAdopter::moveTreeToNewScope(Node& root) const
 {
     ASSERT(needsScopeChange());
 
+#if !ENABLE(OILPAN)
     m_oldScope.guardRef();
+#endif
 
     // If an element is moved from a document and then eventually back again the collection cache for
     // that element may contain stale data as changes made to it will have updated the DOMTreeVersion
@@ -77,7 +79,9 @@ void TreeScopeAdopter::moveTreeToNewScope(Node& root) const
         }
     }
 
+#if !ENABLE(OILPAN)
     m_oldScope.guardDeref();

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

Who keeps the old scope alive while we're moving the tree from the old scope to
the new scope? My question is whether it is safe to trigger GC while moving the
tree.

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

TreeScopeAdopter is STACK_ALLOCATED, so the pointers are on the stack. Marked
TreeScopeAdopter as STACK_ALLOCATED.

+#endif
 }
 
 void TreeScopeAdopter::moveTreeToNewDocument(Node& root, Document& oldDocument, Document& newDocument) const
@@ -106,8 +110,10 @@ inline void TreeScopeAdopter::updateTreeScope(Node& node) const
 {
     ASSERT(!node.isTreeScope());
     ASSERT(node.treeScope() == m_oldScope);
+#if !ENABLE(OILPAN)
     m_newScope.guardRef();
     m_oldScope.guardDeref();
+#endif
     node.setTreeScope(&m_newScope);
 }