Oilpan: move editing objects to the heap.

Source/core/editing/VisibleSelection.cpp

Index: Source/core/editing/VisibleSelection.cpp
diff --git a/Source/core/editing/VisibleSelection.cpp b/Source/core/editing/VisibleSelection.cpp
index 6a79d0460bdb1014b6a2de6b0ee85b7dc1819002..f1b600aea5a8d5552422512c5aa836457841efee 100644
--- a/Source/core/editing/VisibleSelection.cpp
+++ b/Source/core/editing/VisibleSelection.cpp
@@ -136,7 +136,9 @@ VisibleSelection& VisibleSelection::operator=(const VisibleSelection& other)
 
 VisibleSelection::~VisibleSelection()
 {
+#if !ENABLE(OILPAN)
     didChange();
+#endif
 }
 
 VisibleSelection VisibleSelection::selectionFromContentsOfNode(Node* node)
@@ -760,6 +762,14 @@ void VisibleSelection::didChange()
         m_changeObserver->didChangeVisibleSelection();
 }
 
+void VisibleSelection::trace(Visitor* visitor)
+{
+    visitor->trace(m_base);
+    visitor->trace(m_extent);
+    visitor->trace(m_start);
+    visitor->trace(m_end);
+}
+
 #ifndef NDEBUG
 
 void VisibleSelection::debugPosition() const