Oilpan:Allow custom handling of classes that contain weak pointers that are embedded in collections.

Source/wtf/LinkedHashSet.h

Index: Source/wtf/LinkedHashSet.h
diff --git a/Source/wtf/LinkedHashSet.h b/Source/wtf/LinkedHashSet.h
index eb235d4ee7de6cfe8608ece4834bc1e339b0c443..eec38082385e8a1ff35035862643269689a67b7d 100644
--- a/Source/wtf/LinkedHashSet.h
+++ b/Source/wtf/LinkedHashSet.h
@@ -307,7 +307,7 @@ struct LinkedHashSetTraits : public SimpleClassHashTraits<LinkedHashSetNode<Valu
     static const bool emptyValueIsZero = true;
 
     static const bool hasIsEmptyValueFunction = true;
-    static bool isEmptyValue(const Node& value) { return !value.m_next; }
+    static bool isEmptyValue(const Node& node) { return !node.m_next; }
 
     static const int deletedValue = -1;
 
@@ -325,6 +325,11 @@ struct LinkedHashSetTraits : public SimpleClassHashTraits<LinkedHashSetNode<Valu
         static const bool value = ValueTraits::template NeedsTracingLazily<>::value;
     };
     static const bool isWeak = ValueTraits::isWeak;
+    template<typename Visitor>
+    static bool shouldRemoveFromCollection(Visitor* visitor, LinkedHashSetNode<Value>& node)
+    {
+        return ValueTraits::shouldRemoveFromCollection(visitor, node.m_value);
+    }
 };
 
 template<typename LinkedHashSetType>