Oilpan: Prepare to move ImageLoader and its subclasses to Oilpan heap.

Source/core/svg/SVGImageElement.h

Index: Source/core/svg/SVGImageElement.h
diff --git a/Source/core/svg/SVGImageElement.h b/Source/core/svg/SVGImageElement.h
index 8dc02d4e795bd04e95d195c8951e971fbf39c43a..d4699b9809bda57a9697daea8ce62afad9b8e5a7 100644
--- a/Source/core/svg/SVGImageElement.h
+++ b/Source/core/svg/SVGImageElement.h
@@ -35,6 +35,7 @@ class SVGImageElement FINAL : public SVGGraphicsElement,
                               public SVGURIReference {
 public:
     DEFINE_NODE_FACTORY(SVGImageElement);
+    virtual void trace(Visitor*) OVERRIDE;
 
     bool currentFrameHasSingleSecurityOrigin() const;
 
@@ -66,6 +67,7 @@ private:
 
     virtual bool selfHasRelativeLengths() const OVERRIDE;
     virtual void didMoveToNewDocument(Document& oldDocument) OVERRIDE;
+    SVGImageLoader& imageLoader() { return *m_imageLoader; }
 
     RefPtr<SVGAnimatedLength> m_x;
     RefPtr<SVGAnimatedLength> m_y;
@@ -73,7 +75,7 @@ private:
     RefPtr<SVGAnimatedLength> m_height;
     RefPtr<SVGAnimatedPreserveAspectRatio> m_preserveAspectRatio;
 
-    SVGImageLoader m_imageLoader;
+    OwnPtrWillBeMember<SVGImageLoader> m_imageLoader;
     bool m_needsLoaderURIUpdate : 1;
 };