Improve DEFINE_STATIC_LOCAL()'s handling of Blink GCed objects.

third_party/WebKit/Source/core/html/HTMLSourceElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2010 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 24 matching lines @@
 #include "core/html/HTMLMediaElement.h"
 #include "core/html/HTMLPictureElement.h"
 #include "platform/Logging.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
 static SourceEventSender& sourceErrorEventSender()
 {
-    DEFINE_STATIC_LOCAL(Persistent<SourceEventSender>, sharedErrorEventSender, (SourceEventSender::create(EventTypeNames::error)));
-    return *sharedErrorEventSender;
+    DEFINE_STATIC_LOCAL(SourceEventSender, sharedErrorEventSender, (SourceEventSender::create(EventTypeNames::error)));
+    return sharedErrorEventSender;
 }
 
 class HTMLSourceElement::Listener final : public MediaQueryListListener {
 public:
     explicit Listener(HTMLSourceElement* element) : m_element(element) { }
     void notifyMediaQueryChanged() override
     {
         if (m_element)
             m_element->notifyMediaQueryChanged();
     }
@@ skipping 133 matching lines @@
 }
 
 DEFINE_TRACE(HTMLSourceElement)
 {
     visitor->trace(m_mediaQueryList);
     visitor->trace(m_listener);
     HTMLElement::trace(visitor);
 }
 
 } // namespace blink