Fix edge case bugs of canvas arc.

Source/core/html/canvas/CanvasPathMethods.h

Index: Source/core/html/canvas/CanvasPathMethods.h
diff --git a/Source/core/html/canvas/CanvasPathMethods.h b/Source/core/html/canvas/CanvasPathMethods.h
index 3259697dcc1276a19a9c6823e08d00789dc06ad9..675d41b2440b1147490a1df512eff42dae28f636 100644
--- a/Source/core/html/canvas/CanvasPathMethods.h
+++ b/Source/core/html/canvas/CanvasPathMethods.h
@@ -47,7 +47,7 @@ public:
     void quadraticCurveTo(float cpx, float cpy, float x, float y);
     void bezierCurveTo(float cp1x, float cp1y, float cp2x, float cp2y, float x, float y);
     void arcTo(float x0, float y0, float x1, float y1, float radius, ExceptionCode&);
-    void arc(float x, float y, float r, float sa, float ea, bool anticlockwise, ExceptionCode&);
+    void arc(float x, float y, float radius, float startAngle, float endAngle, bool anticlockwise, ExceptionCode&);
     void rect(float x, float y, float width, float height);
 
     virtual bool isTransformInvertible() const { return true; }