Add null check to fill, stroke, clip method

LayoutTests/fast/canvas/script-tests/canvas-path-context-clip.js

Index: LayoutTests/fast/canvas/script-tests/canvas-path-context-clip.js
diff --git a/LayoutTests/fast/canvas/script-tests/canvas-path-context-clip.js b/LayoutTests/fast/canvas/script-tests/canvas-path-context-clip.js
index 78e02570e47cb00b8b629cd0de566debb65cf1ea..cff4d5ceae805a6981a40136b8b2dd1e6bc77913 100644
--- a/LayoutTests/fast/canvas/script-tests/canvas-path-context-clip.js
+++ b/LayoutTests/fast/canvas/script-tests/canvas-path-context-clip.js
@@ -66,6 +66,12 @@ function prepareTestScenario() {
     // Test exception cases.
     shouldThrow("ctx.clip(null)");
     shouldThrow("ctx.clip(null, null)");
+    shouldThrow("ctx.clip(null, 'nonzero')");
+    shouldThrow("ctx.clip([], 'nonzero')");
+    shouldThrow("ctx.clip({}, 'nonzero')");
+    shouldThrow("ctx.clip(null, 'evenodd')");
+    shouldThrow("ctx.clip([], 'evenodd')");
+    shouldThrow("ctx.clip({}, 'evenodd')");
 }
 
 // Run test and allow variation of results.