[S.P.] Use 'const LayoutObject&' in SVGMaskPainter.

Source/core/paint/SVGMaskPainter.h

Index: Source/core/paint/SVGMaskPainter.h
diff --git a/Source/core/paint/SVGMaskPainter.h b/Source/core/paint/SVGMaskPainter.h
index 42d829cc0b5b0af3020d38846bc07a044420fc34..e1b6998a0fd02fc37ae8c14c34db8ca9b934b84a 100644
--- a/Source/core/paint/SVGMaskPainter.h
+++ b/Source/core/paint/SVGMaskPainter.h
@@ -18,8 +18,8 @@ class SVGMaskPainter {
 public:
     SVGMaskPainter(LayoutSVGResourceMasker& mask) : m_mask(mask) { }
 
-    bool prepareEffect(LayoutObject*, GraphicsContext*);
-    void finishEffect(LayoutObject*, GraphicsContext*);
+    bool prepareEffect(const LayoutObject&, GraphicsContext*);
+    void finishEffect(const LayoutObject&, GraphicsContext*);
 
 private:
     void drawMaskForRenderer(GraphicsContext*, DisplayItemClient, const FloatRect& targetBoundingBox);