InlinedVisitor: Migrate dom to use inlined tracing

Source/core/dom/custom/CustomElementMicrotaskDispatcher.cpp

 // 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.
 
 #include "config.h"
 #include "core/dom/custom/CustomElementMicrotaskDispatcher.h"
 
 #include "core/dom/Microtask.h"
 #include "core/dom/custom/CustomElementCallbackQueue.h"
 #include "core/dom/custom/CustomElementMicrotaskImportStep.h"
@@ skipping 64 matching lines @@
         // Created callback may enqueue an attached callback.
         CustomElementProcessingStack::CallbackDeliveryScope scope;
         element->processInElementQueue(kMicrotaskQueueId);
     }
 
     m_elements.clear();
     CustomElementScheduler::microtaskDispatcherDidFinish();
     m_phase = Quiescent;
 }
 
-void CustomElementMicrotaskDispatcher::trace(Visitor* visitor)
+DEFINE_TRACE(CustomElementMicrotaskDispatcher)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_elements);
 #endif
 }
 
 } // namespace blink