Add null check to fill, stroke, clip method

Source/core/html/canvas/CanvasRenderingContext2D.idl

Index: Source/core/html/canvas/CanvasRenderingContext2D.idl
diff --git a/Source/core/html/canvas/CanvasRenderingContext2D.idl b/Source/core/html/canvas/CanvasRenderingContext2D.idl
index 970d4ff7b3eb84ac22245cd42cbb89e0001d522e..8c8eb6eca983c6696f5d45193697ee64d148cd64 100644
--- a/Source/core/html/canvas/CanvasRenderingContext2D.idl
+++ b/Source/core/html/canvas/CanvasRenderingContext2D.idl
@@ -78,16 +78,16 @@ interface CanvasRenderingContext2D : CanvasRenderingContext {
 
     // FIXME: Simplify these using optional CanvasWindingRule once crbug.com/339000 gets fixed.
     void fill();
-    [RuntimeEnabled=ExperimentalCanvasFeatures] void fill(Path path);
+    [RuntimeEnabled=ExperimentalCanvasFeatures, RaisesException] void fill(Path? path);
     void fill(CanvasWindingRule winding);
-    [RuntimeEnabled=ExperimentalCanvasFeatures] void fill(Path path, CanvasWindingRule winding);
+    [RuntimeEnabled=ExperimentalCanvasFeatures, RaisesException] void fill(Path? path, CanvasWindingRule winding);
     void stroke();
-    [RuntimeEnabled=ExperimentalCanvasFeatures] void stroke(Path path);
+    [RuntimeEnabled=ExperimentalCanvasFeatures, RaisesException] void stroke(Path? path);
     // FIXME: Simplify these using optional CanvasWindingRule once crbug.com/339000 gets fixed.
     void clip();
-    [RuntimeEnabled=ExperimentalCanvasFeatures] void clip(Path path);
+    [RuntimeEnabled=ExperimentalCanvasFeatures, RaisesException] void clip(Path? path);
     void clip(CanvasWindingRule winding);
-    [RuntimeEnabled=ExperimentalCanvasFeatures] void clip(Path path, CanvasWindingRule winding);
+    [RuntimeEnabled=ExperimentalCanvasFeatures, RaisesException] void clip(Path? path, CanvasWindingRule winding);
     boolean isPointInPath(float x, float y, optional CanvasWindingRule winding);
     boolean isPointInStroke(float x, float y);