InlinedVisitor: Migrate dom to use inlined tracing

Source/core/dom/IdTargetObserver.cpp

 /*
  * Copyright (C) 2012 Google Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 26 matching lines @@
     registry().addObserver(m_id, this);
 }
 
 IdTargetObserver::~IdTargetObserver()
 {
 #if !ENABLE(OILPAN)
     registry().removeObserver(m_id, this);
 #endif
 }
 
-void IdTargetObserver::trace(Visitor* visitor)
+DEFINE_TRACE(IdTargetObserver)
 {
     visitor->trace(m_registry);
 }
 
 void IdTargetObserver::unregister()
 {
 #if ENABLE(OILPAN)
     registry().removeObserver(m_id, this);
 #endif
 }
 
 } // namespace blink