Hollow out more of the tracing system in oilpan

sky/engine/bindings/core/v8/Nullable.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef Nullable_h
 #define Nullable_h
 
 #include "platform/heap/Handle.h"
 #include "wtf/Assertions.h"
 
@@ skipping 33 matching lines @@
 
     // See comment in RefPtr.h about what UnspecifiedBoolType is.
     typedef const T* UnspecifiedBoolType;
     operator UnspecifiedBoolType() const { return m_isNull ? 0 : &m_value; }
 
     bool operator==(const Nullable& other) const
     {
         return (m_isNull && other.m_isNull) || (!m_isNull && !other.m_isNull && m_value == other.m_value);
     }
 
-    void trace(Visitor* visitor)
-    {
-        TraceIfNeeded<T>::trace(visitor, &m_value);
-    }
-
 private:
     T m_value;
     bool m_isNull;
 };
 
 } // namespace blink
 
 #endif // Nullable_h