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

third_party/WebKit/Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 130 matching lines @@
 // We need to retain the scroll customization callbacks until the element
 // they're associated with is destroyed. It would be simplest if the callbacks
 // could be stored in ElementRareData, but we can't afford the space
 // increase. Instead, keep the scroll customization callbacks here. The other
 // option would be to store these callbacks on the FrameHost or document, but
 // that necessitates a bunch more logic for transferring the callbacks between
 // FrameHosts when elements are moved around.
 ScrollCustomizationCallbacks& scrollCustomizationCallbacks()
 {
     ASSERT(RuntimeEnabledFeatures::scrollCustomizationEnabled());
-    DEFINE_STATIC_LOCAL(Persistent<ScrollCustomizationCallbacks>,
-        scrollCustomizationCallbacks, (new ScrollCustomizationCallbacks()));
-    return *scrollCustomizationCallbacks;
+    DEFINE_STATIC_LOCAL(ScrollCustomizationCallbacks, scrollCustomizationCallbacks, (new ScrollCustomizationCallbacks));
+    return scrollCustomizationCallbacks;
 }
 
 } // namespace
 
 using namespace HTMLNames;
 using namespace XMLNames;
 
 enum class ClassStringContent { Empty, WhiteSpaceOnly, HasClasses };
 
 RawPtr<Element> Element::create(const QualifiedName& tagName, Document* document)
@@ skipping 3506 matching lines @@
 {
 #if ENABLE(OILPAN)
     if (hasRareData())
         visitor->trace(elementRareData());
     visitor->trace(m_elementData);
 #endif
     ContainerNode::trace(visitor);
 }
 
 } // namespace blink