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

third_party/WebKit/Source/core/layout/svg/LayoutSVGResourceContainer.cpp

 /*
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 271 matching lines @@
         return;
 
     SVGElementSet* dependencies = toSVGElement(object->node())->setOfIncomingReferences();
     if (!dependencies)
         return;
 
     // We allow cycles in SVGDocumentExtensions reference sets in order to avoid expensive
     // reference graph adjustments on changes, so we need to break possible cycles here.
     // This strong reference is safe, as it is guaranteed that this set will be emptied
     // at the end of recursion.
-    DEFINE_STATIC_LOCAL(Persistent<SVGElementSet>, invalidatingDependencies, (new SVGElementSet));
+    DEFINE_STATIC_LOCAL(SVGElementSet, invalidatingDependencies, (new SVGElementSet));
 
     for (SVGElement* element : *dependencies) {
         if (LayoutObject* layoutObject = element->layoutObject()) {
-            if (UNLIKELY(!invalidatingDependencies->add(element).isNewEntry)) {
+            if (UNLIKELY(!invalidatingDependencies.add(element).isNewEntry)) {
                 // Reference cycle: we are in process of invalidating this dependant.
                 continue;
             }
 
             LayoutSVGResourceContainer::markForLayoutAndParentResourceInvalidation(layoutObject, needsLayout);
-            invalidatingDependencies->remove(element);
+            invalidatingDependencies.remove(element);
         }
     }
 }
 
 void LayoutSVGResourceContainer::markForLayoutAndParentResourceInvalidation(LayoutObject* object, bool needsLayout)
 {
     ASSERT(object);
     ASSERT(object->node());
 
     if (needsLayout && !object->documentBeingDestroyed())
@@ skipping 10 matching lines @@
             // This will process the rest of the ancestors.
             toLayoutSVGResourceContainer(current)->removeAllClientsFromCache();
             break;
         }
 
         current = current->parent();
     }
 }
 
 } // namespace blink