Revert of HTMLImageElement: do not use fallback content for ImageDocument

third_party/WebKit/LayoutTests/http/tests/images/png-partial-load-as-document.html

-<iframe style="background-color: blue; width: 320px; height: 240px;"></iframe>
-<!--
-Tests that when a progressive png is loaded as document, the image is shown
-progressively during loading.
-The result image should show the dice image partially.
--->
-<script>
-if (window.testRunner) {
-    testRunner.dumpAsTextWithPixelResults();
-    testRunner.waitUntilDone();
-}
-
-function loadAndStall()
-{
-    return "http://127.0.0.1:8000/resources/load-and-stall.php";
-}
-
-function pngImage()
-{
-    return "?name=../../../fast/images/resources/dice.png&mimeType=image%2Fpng";
-}
-
-function testDone()
-{
-    if (window.testRunner) {
-        window.stop();
-        testRunner.notifyDone();
-    }
-}
-
-function runTest()
-{
-    document.querySelector("iframe").src = loadAndStall() + pngImage() + "&stallAt=45057&stallFor=60";
-    setTimeout(testDone, 500);
-}
-
-window.onload = function() {
-    setTimeout(runTest, 0);
-}
-</script>