Make callback arg non-nullable on canvas.toBlob

third_party/WebKit/LayoutTests/fast/canvas/canvas-toBlob-invalid-expected.txt

Index: third_party/WebKit/LayoutTests/fast/canvas/canvas-toBlob-invalid-expected.txt
diff --git a/third_party/WebKit/LayoutTests/fast/canvas/canvas-toBlob-invalid-expected.txt b/third_party/WebKit/LayoutTests/fast/canvas/canvas-toBlob-invalid-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..cbe19275721ffc7196002de5184282c77ae040c2
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/fast/canvas/canvas-toBlob-invalid-expected.txt
@@ -0,0 +1,14 @@
+Test the handling of invalid arguments in canvas toBlob().
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS canvas.toBlob(); threw exception TypeError: Failed to execute 'toBlob' on 'HTMLCanvasElement': 1 argument required, but only 0 present..
+PASS canvas.toBlob(null); threw exception TypeError: Failed to execute 'toBlob' on 'HTMLCanvasElement': The callback provided as parameter 1 is not a function..
+PASS canvas.toBlob(undefined); threw exception TypeError: Failed to execute 'toBlob' on 'HTMLCanvasElement': The callback provided as parameter 1 is not a function..
+PASS canvas.toBlob(function() {}); did not throw exception.
+PASS canvas.toBlob(function(blob) {}, 'image/jpeg', 500) did not throw exception.
+PASS successfullyParsed is true
+
+TEST COMPLETE
+