Add a missing null check for FontFaceSet::document()

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

 /*
  * 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 330 matching lines @@
         return m_nonCSSConnectedFaces.size();
     return cssConnectedFontFaceList().size() + m_nonCSSConnectedFaces.size();
 }
 
 void FontFaceSet::fireDoneEventIfPossible()
 {
     if (m_shouldFireLoadingEvent)
         return;
     if (!shouldSignalReady())
         return;
+    Document* d = document();
+    if (!d)
+        return;
 
     // If the layout was invalidated in between when we thought layout
     // was updated and when we're ready to fire the event, just wait
     // until after the next layout before firing events.
-    Document* d = document();
     if (!d->view() || d->view()->needsLayout())
         return;
 
     if (m_isLoading) {
         FontFaceSetLoadEvent* doneEvent = nullptr;
         FontFaceSetLoadEvent* errorEvent = nullptr;
         doneEvent = FontFaceSetLoadEvent::createForFontFaces(EventTypeNames::loadingdone, m_loadedFonts);
         m_loadedFonts.clear();
         if (!m_failedFonts.isEmpty()) {
             errorEvent = FontFaceSetLoadEvent::createForFontFaces(EventTypeNames::loadingerror, m_failedFonts);
@@ skipping 184 matching lines @@
     visitor->trace(m_loadedFonts);
     visitor->trace(m_failedFonts);
     visitor->trace(m_nonCSSConnectedFaces);
     visitor->trace(m_asyncRunner);
     EventTargetWithInlineData::trace(visitor);
     Supplement<Document>::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 } // namespace blink