Extract the SVG Filter Reference implementation out of the FilterEffectRenderer into its own type

Source/core/platform/graphics/filters/FilterOperation.h

Index: Source/core/platform/graphics/filters/FilterOperation.h
diff --git a/Source/core/platform/graphics/filters/FilterOperation.h b/Source/core/platform/graphics/filters/FilterOperation.h
index e200717b7f96ca51aa87bd3fd7a56bf727ce00a2..d2960633bfc4802b7be64ec572dc138c3115657d 100644
--- a/Source/core/platform/graphics/filters/FilterOperation.h
+++ b/Source/core/platform/graphics/filters/FilterOperation.h
@@ -32,6 +32,7 @@
 #include "core/platform/graphics/LayoutSize.h"
 #include "core/platform/graphics/filters/Filter.h"
 #include "core/platform/graphics/filters/FilterEffect.h"
+#include "core/platform/graphics/filters/ReferenceFilter.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefCounted.h"
@@ -162,8 +163,8 @@ public:
     CachedSVGDocumentReference* cachedSVGDocumentReference() const { return m_cachedSVGDocumentReference.get(); }
     void setCachedSVGDocumentReference(PassOwnPtr<CachedSVGDocumentReference> cachedSVGDocumentReference) { m_cachedSVGDocumentReference = cachedSVGDocumentReference; }
 
-    FilterEffect* filterEffect() const { return m_filterEffect.get(); }
-    void setFilterEffect(PassRefPtr<FilterEffect> filterEffect, PassRefPtr<Filter> filter) { m_filterEffect = filterEffect; m_filter = filter; }
+    ReferenceFilter* filter() const { return m_filter.get(); }
+    void setFilter(PassRefPtr<ReferenceFilter> filter) { m_filter = filter; }
 
 private:
 
@@ -185,8 +186,7 @@ private:
     String m_url;
     String m_fragment;
     OwnPtr<CachedSVGDocumentReference> m_cachedSVGDocumentReference;
-    RefPtr<FilterEffect> m_filterEffect;
-    RefPtr<Filter> m_filter;
+    RefPtr<ReferenceFilter> m_filter;
 };
 
 // GRAYSCALE, SEPIA, SATURATE and HUE_ROTATE are variations on a basic color matrix effect.