[ServiceWorker] Make fetch() method better conformance with the spec.

LayoutTests/http/tests/serviceworker/resources/fetch-access-control-iframe.html

+<script>
+function onMessage(event) {
+    var script = document.createElement('script');
+    script.src = event.data.url;
+    script.addEventListener(
+        'error',
+        function() { report({jsonpResult:'error'}); });
+    document.body.appendChild(script);
+}
+function report(data) {
+    window.parent.postMessage(
+        data,
+        'http://127.0.0.1:8000');
+}
+function onload() {
+    window.addEventListener('message', onMessage, false);
+}
+window.addEventListener('load', onload);
+</script>

[falken, 2014/07/25 05:41:29]

This is also a new file and should conform to new style guide (2 space indent)

[horo, 2014/07/25 06:00:55]

Done.