Refactor m_absoluteTransform out of SVGFilter and into base class.

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

Index: Source/core/platform/graphics/filters/Filter.h
diff --git a/Source/core/platform/graphics/filters/Filter.h b/Source/core/platform/graphics/filters/Filter.h
index d410200b838b7527c5e9bf9bdbecebe211437540..b37316a6da023aba0751a44a817ade45365e27e0 100644
--- a/Source/core/platform/graphics/filters/Filter.h
+++ b/Source/core/platform/graphics/filters/Filter.h
@@ -31,7 +31,7 @@ class FilterEffect;
 
 class Filter : public RefCounted<Filter> {
 public:
-    Filter() : m_renderingMode(Unaccelerated) { }
+    Filter(const AffineTransform& absoluteTransform) : m_absoluteTransform(absoluteTransform), m_renderingMode(Unaccelerated) { }
     virtual ~Filter() { }
 
     void setSourceImage(PassOwnPtr<ImageBuffer> sourceImage) { m_sourceImage = sourceImage; }
@@ -40,6 +40,9 @@ public:
     FloatSize filterResolution() const { return m_filterResolution; }
     void setFilterResolution(const FloatSize& filterResolution) { m_filterResolution = filterResolution; }
 
+    const AffineTransform& absoluteTransform() const { return m_absoluteTransform; }
+    FloatPoint mapAbsolutePointToLocalPoint(const FloatPoint& point) const { return m_absoluteTransform.inverse().mapPoint(point); }
+
     RenderingMode renderingMode() const { return m_renderingMode; }
     void setRenderingMode(RenderingMode renderingMode) { m_renderingMode = renderingMode; }
 
@@ -49,12 +52,12 @@ public:
     virtual FloatRect sourceImageRect() const = 0;
     virtual FloatRect filterRegion() const = 0;
     
-    virtual FloatPoint mapAbsolutePointToLocalPoint(const FloatPoint&) const { return FloatPoint(); }
 
 private:
     OwnPtr<ImageBuffer> m_sourceImage;
     FloatSize m_filterResolution;
     RenderingMode m_renderingMode;
+    AffineTransform m_absoluteTransform;
 };
 
 } // namespace WebCore