Make callback arg non-nullable on canvas.toBlob

third_party/WebKit/LayoutTests/fast/canvas/canvas-toBlob-invalid.html

Index: third_party/WebKit/LayoutTests/fast/canvas/canvas-toBlob-invalid.html
diff --git a/third_party/WebKit/LayoutTests/fast/canvas/canvas-toBlob-invalid.html b/third_party/WebKit/LayoutTests/fast/canvas/canvas-toBlob-invalid.html
new file mode 100644
index 0000000000000000000000000000000000000000..c4633f273419f458f2126c1a95c83018b7f7c9c7
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/fast/canvas/canvas-toBlob-invalid.html
@@ -0,0 +1,18 @@
+<script src="../../resources/js-test.js"></script>
+<script type='text/javascript'>
+description("Test the handling of invalid arguments in canvas toBlob().");
+
+var canvas = document.createElement('canvas');
+var ctx = canvas.getContext("2d"); 
+ctx.strokeStyle = "red";
+ctx.strokeRect(0, 0, 50, 50);
+
+shouldThrow("canvas.toBlob();");
+shouldThrow("canvas.toBlob(null);");
+shouldThrow("canvas.toBlob(undefined);");

[Noel Gordon, 2015/12/11 01:01:45]

The way it's going, we should add 

shouldThrow("canvas.toBlob(42);");

for posterity :)

+// Passing the callback argument without blob handle silently fails.
+shouldNotThrow("canvas.toBlob(function() {});");
+
+// Invalid quality argument will fall back to default value
+shouldNotThrow("canvas.toBlob(function(blob) {}, 'image/jpeg', 500)");
+</script>