blink_gc_plugin should require tracing for classes that have a trace method

third_party/WebKit/Source/core/events/EventTarget.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  *           (C) 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ skipping 201 matching lines @@
 
   bool clearAttributeEventListener(const AtomicString& eventType);
 
   friend class EventListenerIterator;
 };
 
 // EventTargetData is a GCed object, so it should not be used as a part of
 // object. However, we intentionally use it as a part of object for performance,
 // assuming that no one extracts a pointer of
 // EventTargetWithInlineData::m_eventTargetData and store it to a Member etc.
-class GC_PLUGIN_IGNORE("513199") CORE_EXPORT EventTargetWithInlineData
-    : public EventTarget {
+class CORE_EXPORT EventTargetWithInlineData : public EventTarget {
  public:
   ~EventTargetWithInlineData() override {}
 
   DEFINE_INLINE_VIRTUAL_TRACE() {
     visitor->trace(m_eventTargetData);
     EventTarget::trace(visitor);
   }
 
  protected:
   EventTargetData* eventTargetData() final { return &m_eventTargetData; }
   EventTargetData& ensureEventTargetData() final { return m_eventTargetData; }
 
  private:
+  GC_PLUGIN_IGNORE("513199")
   EventTargetData m_eventTargetData;
 };
 
 // FIXME: These macros should be split into separate DEFINE and DECLARE
 // macros to avoid causing so many header includes.
 #define DEFINE_ATTRIBUTE_EVENT_LISTENER(attribute)                        \
   EventListener* on##attribute() {                                        \
     return this->getAttributeEventListener(EventTypeNames::attribute);    \
   }                                                                       \
   void setOn##attribute(EventListener* listener) {                        \
@@ skipping 71 matching lines @@
     const AtomicString& eventType) {
   EventTargetData* d = eventTargetData();
   if (!d)
     return false;
   return d->eventListenerMap.containsCapturing(eventType);
 }
 
 }  // namespace blink
 
 #endif  // EventTarget_h