Oilpan: move RenderObjects off heap.

Source/core/rendering/svg/RenderSVGResourceFilter.h

Index: Source/core/rendering/svg/RenderSVGResourceFilter.h
diff --git a/Source/core/rendering/svg/RenderSVGResourceFilter.h b/Source/core/rendering/svg/RenderSVGResourceFilter.h
index 43a80f07dcaeecebc4c04273ec18710a29faca80..7b94ca14ab279eb6b4c2da6d8824fe6b1b4eef63 100644
--- a/Source/core/rendering/svg/RenderSVGResourceFilter.h
+++ b/Source/core/rendering/svg/RenderSVGResourceFilter.h
@@ -60,7 +60,6 @@ public:
     explicit RenderSVGResourceFilter(SVGFilterElement*);
 
     virtual ~RenderSVGResourceFilter();
-    virtual void trace(Visitor*) override;
     virtual void destroy() override;
 
     virtual bool isChildAllowed(RenderObject*, RenderStyle*) const override;
@@ -89,7 +88,7 @@ public:
     virtual RenderSVGResourceType resourceType() const override { return s_resourceType; }
 
 private:
-    typedef WillBeHeapHashMap<RawPtrWillBeMember<RenderObject>, OwnPtrWillBeMember<FilterData> > FilterMap;
+    typedef WillBePersistentHeapHashMap<RenderObject*, OwnPtrWillBeMember<FilterData>> FilterMap;
     FilterMap m_filter;
 };