Implement SVG masking with slimming paint

Source/platform/graphics/GraphicsContext.h

Index: Source/platform/graphics/GraphicsContext.h
diff --git a/Source/platform/graphics/GraphicsContext.h b/Source/platform/graphics/GraphicsContext.h
index 0ef3cc1e3b805193a5ef687137507b56eb4bec01..3cae30dbe0ab11780a3291d0222c986ff044cdc5 100644
--- a/Source/platform/graphics/GraphicsContext.h
+++ b/Source/platform/graphics/GraphicsContext.h
@@ -390,6 +390,8 @@ public:
     void setInDrawingRecorder(bool);
 #endif
 
+    static PassRefPtr<SkColorFilter> WebCoreColorFilterToSkiaColorFilter(ColorFilter);
+
 private:
     const GraphicsContextState* immutableState() const { return m_paintState; }
 
@@ -402,8 +404,6 @@ private:
     static void setPathFromPoints(SkPath*, size_t, const FloatPoint*);
     static void setRadii(SkVector*, FloatSize, FloatSize, FloatSize, FloatSize);
 
-    static PassRefPtr<SkColorFilter> WebCoreColorFilterToSkiaColorFilter(ColorFilter);
-
 #if OS(MACOSX)
     static inline int focusRingOutset(int offset) { return offset + 2; }
     static inline int focusRingWidth(int width) { return width; }