Tracing HeapListHashSet<> iterators.

third_party/WebKit/Source/core/css/CSSSegmentedFontFace.cpp

 /*
  * Copyright (C) 2008 Apple 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 173 matching lines @@
 void CSSSegmentedFontFace::match(const String& text,
                                  HeapVector<Member<FontFace>>& faces) const {
   for (const auto& fontFace : m_fontFaces) {
     if (fontFace->cssFontFace()->ranges()->intersectsWith(text))
       faces.push_back(fontFace);
   }
 }
 
 DEFINE_TRACE(CSSSegmentedFontFace) {
   visitor->trace(m_fontSelector);
+  visitor->trace(m_firstNonCssConnectedFace);
   visitor->trace(m_fontFaces);
 }
 
 }  // namespace blink