Oilpan: promptly release FilterData on LayoutSVGResourceFilter destruction

Source/core/layout/svg/LayoutSVGResourceFilter.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005 Rob Buis <buis@kde.org>
  * Copyright (C) 2005 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * 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
@@ skipping 38 matching lines @@
         ReadyToPaint,
         PaintingFilter,
         PaintingFilterCycleDetected
     };
 
     static PassOwnPtrWillBeRawPtr<FilterData> create()
     {
         return adoptPtrWillBeNoop(new FilterData());
     }
 
+    void dispose();
+
     DECLARE_TRACE();
 
     RefPtrWillBeMember<SVGFilter> filter;
     RefPtrWillBeMember<SVGFilterBuilder> builder;
     OwnPtr<DisplayItemList> m_displayItemList;
     OwnPtr<GraphicsContext> m_context;
     FloatRect boundaries;
     FilterDataState m_state;
 
 private:
@@ skipping 24 matching lines @@
 
     void primitiveAttributeChanged(LayoutObject*, const QualifiedName&);
 
     static const LayoutSVGResourceType s_resourceType = FilterResourceType;
     virtual LayoutSVGResourceType resourceType() const override { return s_resourceType; }
 
     FilterData* getFilterDataForLayoutObject(LayoutObject* object) { return m_filter.get(object); }
     void setFilterDataForLayoutObject(LayoutObject* object, PassOwnPtrWillBeRawPtr<FilterData> filterData) { m_filter.set(object, filterData); }
 
 private:
-    typedef WillBePersistentHeapHashMap<LayoutObject*, OwnPtrWillBeMember<FilterData>> FilterMap;
+    void disposeFilterMap();
+
+    using FilterMap = WillBePersistentHeapHashMap<LayoutObject*, OwnPtrWillBeMember<FilterData>>;
     FilterMap m_filter;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutSVGResourceFilter, isSVGResourceFilter());
 
 }
 
 #endif