[SVG] SVGAnimatedString{,List} migration to new SVG property impl.

Source/core/svg/SVGFEOffsetElement.h

Index: Source/core/svg/SVGFEOffsetElement.h
diff --git a/Source/core/svg/SVGFEOffsetElement.h b/Source/core/svg/SVGFEOffsetElement.h
index 6762a488ab21294b58eb137543153cc800820f27..4e7dba9ef74c47ef71afabc853ac4ba6d7957461 100644
--- a/Source/core/svg/SVGFEOffsetElement.h
+++ b/Source/core/svg/SVGFEOffsetElement.h
@@ -33,6 +33,7 @@ public:
 
     SVGAnimatedNumber* dx() { return m_dx.get(); }
     SVGAnimatedNumber* dy() { return m_dy.get(); }
+    SVGAnimatedString* in1() { return m_in1.get(); }
 private:
     explicit SVGFEOffsetElement(Document&);
 
@@ -43,8 +44,8 @@ private:
 
     RefPtr<SVGAnimatedNumber> m_dx;
     RefPtr<SVGAnimatedNumber> m_dy;
+    RefPtr<SVGAnimatedString> m_in1;
     BEGIN_DECLARE_ANIMATED_PROPERTIES(SVGFEOffsetElement)
-        DECLARE_ANIMATED_STRING(In1, in1)
     END_DECLARE_ANIMATED_PROPERTIES
 };