Remove more bits of the Oilpan tracing system

sky/engine/wtf/HashTable.h

Index: sky/engine/wtf/HashTable.h
diff --git a/sky/engine/wtf/HashTable.h b/sky/engine/wtf/HashTable.h
index 53d27d5dfc26016bf05fb8c60142b743f4afa0c9..5c7b3be1009393b3c9b386a23d852f2d6e349e2d 100644
--- a/sky/engine/wtf/HashTable.h
+++ b/sky/engine/wtf/HashTable.h
@@ -477,8 +477,6 @@ namespace WTF {
         template<typename HashTranslator, typename T> ValueType* lookup(T);
         template<typename HashTranslator, typename T> const ValueType* lookup(T) const;
 
-        void trace(typename Allocator::Visitor*);
-
 #if ENABLE(ASSERT)
         int64_t modifications() const { return m_modifications; }
         void registerModification() { m_modifications++; }