[SVG Fonts] Fix <font-face> element leak document

Source/core/svg/SVGFontFaceSource.h

Index: Source/core/svg/SVGFontFaceSource.h
diff --git a/Source/core/svg/SVGFontFaceSource.h b/Source/core/svg/SVGFontFaceSource.h
index 9211727a89e0865f1fc712dd172bfb7c6efc32de..2ddd526669e8ef8b0425ab6546672a84f81b5493 100644
--- a/Source/core/svg/SVGFontFaceSource.h
+++ b/Source/core/svg/SVGFontFaceSource.h
@@ -15,12 +15,14 @@ class SVGFontFaceElement;
 
 class SVGFontFaceSource : public CSSFontFaceSource {
 public:
-    SVGFontFaceSource(PassRefPtr<SVGFontFaceElement>);
+    SVGFontFaceSource(SVGFontFaceElement*);
 
 private:
     virtual PassRefPtr<SimpleFontData> createFontData(const FontDescription&) OVERRIDE;
 
-    RefPtr<SVGFontFaceElement> m_svgFontFaceElement;
+    // This is a raw ptr as the element resides in the same document as the FontFace. This is to avoid a reference cycle.
+    // FIXME: Oilpan: This should be a Member when we move SVGFontFaceElement to oilpan.
+    SVGFontFaceElement* m_svgFontFaceElement;
 };
 
 } // namespace WebCore