[ServiceWorker] Fix ASSERT failure in DocumentThreadableLoader::handleResponse().

LayoutTests/http/tests/serviceworker/resources/fetch-request-xhr-iframe.html

 <script src="../../resources/testharness.js"></script>
 <script src="test-helpers.js?pipe=sub"></script>
 <script>
 var host_info = get_host_info();
 
 function get_boundary(headers) {
   var reg = new RegExp('multipart\/form-data; boundary=(.*)');
   for (var i = 0; i < headers.length; ++i) {
     if (headers[i][0] != 'content-type') {
       continue;
@@ skipping 125 matching lines @@
         assert_equals(response.mode, 'cors');
         assert_equals(response.credentials, 'same-origin');
         return xhr_send(host_info['HTTP_REMOTE_ORIGIN'], 'GET', '', true);
       })
     .then(function(response){
         assert_equals(response.mode, 'cors');
         assert_equals(response.credentials, 'include');
       });
 }
 
+function data_url_test() {
+  return new Promise(function(resolve, reject) {
+        var xhr = new XMLHttpRequest();
+        xhr.onload = function() {
+          resolve(xhr.response);
+        };
+        xhr.onerror = function() {
+          reject('XHR should succeed.');
+        };
+        xhr.responseType = 'text';
+        xhr.open('GET', 'data:text/html,Foobar', true);
+        xhr.send();
+      })
+    .then(function(data) {
+        assert_equals(data, 'Foobar');
+      });
+}
+
+function xhr_options_test() {
+  return new Promise(function(resolve, reject) {
+        var xhr = new XMLHttpRequest();
+        xhr.onload = function() {
+          resolve(xhr.response);
+        };
+        xhr.onerror = function() {
+          reject('XHR should succeed.');
+        };
+        xhr.responseType = 'text';
+        xhr.open('OpTiOnS', 'fetch-access-control.php', true);
+        xhr.send();
+      })
+    .then(function(data) {
+        var result;
+        var report = function(arg) {
+          result = arg;
+        };
+        eval(data);
+        assert_equals(result['jsonpResult'], 'success');
+        assert_equals(result['method'], 'OPTIONS');
+      })
+}
+
 window.addEventListener('message', function(evt) {
     var port = evt.ports[0];
     string_test()
       .then(blob_test)
       .then(custom_method_test)
       .then(form_data_test)
       .then(mode_credentials_test)
+      .then(data_url_test)
+      .then(xhr_options_test)
       .then(function() { port.postMessage({results: 'finish'}); })
       .catch(function(e) { port.postMessage({results: 'failure:' + e}); });
   });
 </script>