Enable srcset support in HTMLImageElement

LayoutTests/http/tests/loading/resources/preloaded.js

+var results=[];
+
+if (window.testRunner) {
+    testRunner.dumpAsText();
+}
+
+function checkForPreload(url, shouldbe) {
+    var preloaded = internals.isPreloaded(url);
+    if ((preloaded && shouldbe) || (!preloaded && !shouldbe))
+        results.push("PASS " + url);
+    else
+        results.push("FAIL " + url);
+}
+
+function printPreloadResults(){
+    for(var i = 0; i < results.length; i++) {
+        document.body.appendChild(document.createElement("br"));
+        document.body.appendChild(document.createTextNode(results[i]));
+    }
+}