InlinedVisitor: Migrate dom to use inlined tracing

Source/core/dom/Iterator.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 Iterator_h
 #define Iterator_h
 
 #include "bindings/core/v8/ScriptValue.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class ExceptionState;
 
 class Iterator : public GarbageCollectedFinalized<Iterator>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     Iterator() { }
     virtual ~Iterator() { }
 
     virtual ScriptValue next(ScriptState*, ExceptionState&) = 0;
     virtual ScriptValue next(ScriptState*, ScriptValue /* value */, ExceptionState&) = 0;
     Iterator* iterator(ScriptState*, ExceptionState&) { return this; }
 
-    virtual void trace(Visitor*) { }
+    DEFINE_INLINE_VIRTUAL_TRACE() { }
 };
 
 } // namespace blink
 
 #endif // Iterator_h