Hollow out more of the tracing system in oilpan

sky/engine/bindings/core/v8/ScriptPromisePropertyBase.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 ScriptPromisePropertyBase_h
 #define ScriptPromisePropertyBase_h
 
 #include "bindings/core/v8/ScopedPersistent.h"
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptPromiseProperties.h"
@@ skipping 21 matching lines @@
 
     enum State {
         Pending,
         Resolved,
         Rejected,
     };
     State state() const { return m_state; }
 
     ScriptPromise promise(DOMWrapperWorld&);
 
-    virtual void trace(Visitor*) { }
-
 protected:
     ScriptPromisePropertyBase(ExecutionContext*, Name);
 
     void resolveOrReject(State targetState);
 
     // ScriptPromiseProperty overrides these to wrap the holder,
     // rejected value and resolved value. The
     // ScriptPromisePropertyBase caller will enter the V8Context for
     // the property's execution context and the world it is
     // creating/settling promises in; the implementation should use
@@ skipping 17 matching lines @@
     v8::Isolate* m_isolate;
     Name m_name;
     State m_state;
 
     WeakPersistentSet m_wrappers;
 };
 
 } // namespace blink
 
 #endif // ScriptPromisePropertyBase_h