Oilpan: move SVG property hierarchy to the heap.

Source/core/svg/SVGUseElement.h

Index: Source/core/svg/SVGUseElement.h
diff --git a/Source/core/svg/SVGUseElement.h b/Source/core/svg/SVGUseElement.h
index c7ee145ea0c3f878c377915a31b0cbf65e7c768d..c38e09f1752f43976c3ea5780650fcb6b8c1a922 100644
--- a/Source/core/svg/SVGUseElement.h
+++ b/Source/core/svg/SVGUseElement.h
@@ -27,6 +27,7 @@
 #include "core/svg/SVGAnimatedLength.h"
 #include "core/svg/SVGGraphicsElement.h"
 #include "core/svg/SVGURIReference.h"
+#include "platform/heap/Handle.h"
 
 namespace blink {
 
@@ -36,6 +37,7 @@ class SVGUseElement final : public SVGGraphicsElement,
                             public SVGURIReference,
                             public DocumentResourceClient {
     DEFINE_WRAPPERTYPEINFO();
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(SVGUseElement);
 public:
     static PassRefPtrWillBeRawPtr<SVGUseElement> create(Document&);
     virtual ~SVGUseElement();
@@ -95,10 +97,10 @@ private:
 
     virtual Timer<SVGElement>* svgLoadEventTimer() override { return &m_svgLoadEventTimer; }
 
-    RefPtr<SVGAnimatedLength> m_x;
-    RefPtr<SVGAnimatedLength> m_y;
-    RefPtr<SVGAnimatedLength> m_width;
-    RefPtr<SVGAnimatedLength> m_height;
+    RefPtrWillBeMember<SVGAnimatedLength> m_x;
+    RefPtrWillBeMember<SVGAnimatedLength> m_y;
+    RefPtrWillBeMember<SVGAnimatedLength> m_width;
+    RefPtrWillBeMember<SVGAnimatedLength> m_height;
 
     bool m_haveFiredLoadEvent;
     bool m_needsShadowTreeRecreation;