Fire load event for an image even if it was the last image we loaded successfully.

LayoutTests/fast/images/onload-event-when-reloading-image-after-successful-image-load.html

+<script>

[esprehn, 2015/03/31 00:34:54]

ditto

+    if (window.testRunner) {
+        testRunner.waitUntilDone();
+        testRunner.dumpAsText();
+    }
+    img = new Image();
+    var onloadCounter = 0;
+    var testImage = 'resources/green.jpg';
+    var resetImage = 'resources/green.jpg';
+    img.onload = function(){ 
+        onloadCounter++;
+        document.getElementById('console').innerHTML += "Image onload event fired for " + img.src.substring(img.src.lastIndexOf('/') + 1) + "<br>";
+        if (onloadCounter == 2) {
+            document.getElementById('result').innerHTML = "PASS";
+            if (window.testRunner)
+                testRunner.notifyDone();
+            return;
+        }
+        if (onloadCounter == 1) {
+            setTimeout("img.src='" + resetImage + "';img.src = '" + testImage + "';", 0);
+            return;
+        }
+        document.getElementById('result').innerHTML = "FAIL";
+    }; 
+    setTimeout("img.src='" + resetImage + "';img.src = '" + testImage + "';", 0);
+</script>
+<div id="console">
+crbug.com/469678: We should fire an image load event even if the image is the last one we loaded successfully.<br>
+In this test we load an image then we immediately launch an other request for the same image - only one load event should be fired.<br>
+Then we do the same again: another load event should be fired.<br>
+</div>
+<div id="result">FAIL</div>