InlinedVisitor: Migrate html to use inlined tracing

Source/core/html/track/vtt/VTTRegionList.h

 /*
  * Copyright (C) 2013 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 32 matching lines @@
     }
 
     unsigned long length() const;
 
     VTTRegion* item(unsigned index) const;
     VTTRegion* getRegionById(const String&) const;
 
     void add(PassRefPtrWillBeRawPtr<VTTRegion>);
     bool remove(VTTRegion*);
 
-    void trace(Visitor*);
+    DECLARE_TRACE();
 
 private:
     VTTRegionList();
 
     WillBeHeapVector<RefPtrWillBeMember<VTTRegion>> m_list;
 };
 
 } // namespace blink
 
 #endif // VTTRegionList_h