Plumb in flag to enable antialiased clipping in HTML 5 Canvas

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 e1ea64f874a750e30615d7840d379160a040e096..a3b44f0365c42e119fd90c70b4b790c3df3ab9c3 100644
--- a/Source/platform/graphics/GraphicsContext.h
+++ b/Source/platform/graphics/GraphicsContext.h
@@ -322,7 +322,7 @@ public:
     // This clip function is used only by <canvas> code. It allows
     // implementations to handle clipping on the canvas differently since
     // the discipline is different.
-    void canvasClip(const Path&, WindRule = RULE_EVENODD);
+    void canvasClip(const Path&, WindRule = RULE_EVENODD, AntiAliasingMode = NotAntiAliased);
 
     void drawText(const Font&, const TextRunPaintInfo&, const FloatPoint&);
     void drawEmphasisMarks(const Font&, const TextRunPaintInfo&, const AtomicString& mark, const FloatPoint&);