[HTMLCanvasElement.toBlob] Default callback version without scheduler

LayoutTests/fast/canvas/canvas-toBlob-jpeg-maximum-quality.html

+<canvas id="mycanvas"></canvas>
+<img id="result" onload="testDone()">

[Justin Novosad, 2015/08/20 20:38:43]

Test is more readable if you set the onload handler near where you set src.

+<script type = 'text/javascript'>
+if (window.testRunner) {
+    testRunner.dumpAsTextWithPixelResults();
+    testRunner.waitUntilDone();
+}
+
+function testDone()
+{
+    if (window.testRunner)
+        testRunner.notifyDone();
+}
+
+var image = new Image();
+image.onload = function() {
+        var canvas = document.getElementById("mycanvas");

[Justin Novosad, 2015/08/20 20:38:42]

indentation

+        canvas.width = image.width;
+        canvas.height = image.height;
+        var ctx = canvas.getContext('2d');
+        ctx.drawImage(image, 0, 0);
+
+        canvas.toBlob(function(blob) {
+            url = URL.createObjectURL(blob);
+            result.src = url;

[Justin Novosad, 2015/08/20 20:38:42]

how come this works? Aren't we missing result =
document.getElementById('result');

[xlai (Olivia), 2015/08/20 21:36:28]

Acknowledged and elsewhere.
I copied this from toDataURL layout test and was also surprised that the webpage
shows correctly the result image. Will changed that to getElementByID as that
looks more secure.

+        }, "image/jpeg", 1.0);
+}
+image.src = "resources/letters.png";
+</script>