Upstream service worker header test to WPT

third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/iso-latin1-header-iframe.html

-<script src="../../resources/testharness.js"></script>
-<script src="test-helpers.js"></script>
-<script>
-
-function xhr_send(method, data) {
-  return new Promise(function(resolve, reject) {
-      var xhr = new XMLHttpRequest();
-      xhr.onload = function() {
-        resolve();
-      };
-      xhr.onerror = function() {
-        reject('XHR must succeed.');
-      };
-      xhr.responseType = 'text';
-      xhr.open(method, './dummy?test', true);
-      xhr.send(data);
-    });
-}
-
-window.addEventListener('message', function(evt) {
-    var port = evt.ports[0];
-    xhr_send('POST', 'test string')
-      .then(function() { port.postMessage({results: 'finish'}); })
-      .catch(function(e) { port.postMessage({results: 'failure:' + e}); });
-  });
-
-</script>