Upstream service worker `fetch` tests to WPT

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

 <script src="../../resources/testharness.js"></script>
 <script src="../../resources/get-host-info.js?pipe=sub"></script>
 <script src="test-helpers.js"></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') {
@@ skipping 49 matching lines @@
   for (const [name, value] of headers) {
     header_names.push(name);
   }
   header_names.sort();
   return header_names;
 }
 
 function get_header_test() {
   return xhr_send(host_info['HTTP_ORIGIN'], 'GET', '', false)
     .then(function(response) {
+        // This assertion is invalid because the User-Agent header should not
+        // be present.
         assert_array_equals(
           get_sorted_header_name_list(response.headers),
           ["accept", "user-agent"],
           'event.request has the expected headers for same-origin GET.');
       });
 }
 
 // TODO(tyoshino): Fix the stack not to include the Origin header as specified
-// in the spec.
+// in the spec. Likewise, the User-Agent header should not be present.
 function post_header_test() {
   return xhr_send(host_info['HTTP_ORIGIN'], 'POST', '', false)
     .then(function(response) {
         assert_array_equals(
           get_sorted_header_name_list(response.headers),
           ["accept", "content-type", "origin", "user-agent"],
           'event.request has the expected headers for same-origin POST.');
       });
 }
 
 function cross_origin_get_header_test() {
   return xhr_send(host_info['HTTP_REMOTE_ORIGIN'], 'GET', '', false)
     .then(function(response) {
+        // This assertion is invalid because the User-Agent header should not
+        // be present.
         assert_array_equals(
           get_sorted_header_name_list(response.headers),
           ["accept", "user-agent"],
           'event.request has the expected headers for cross-origin GET.');
       });
 }
 
 // TODO(tyoshino): Fix the stack not to include the Origin header as specified
-// in the spec.
+// in the spec. Likewise, the User-Agent header should not be present.
 function cross_origin_post_header_test() {
   return xhr_send(host_info['HTTP_REMOTE_ORIGIN'], 'POST', '', false)
     .then(function(response) {
         assert_array_equals(
           get_sorted_header_name_list(response.headers),
           ["accept", "content-type", "origin", "user-agent"],
           'event.request has the expected headers for cross-origin POST.');
       });
 }
 
@@ skipping 122 matching lines @@
       .then(blob_test)
       .then(custom_method_test)
       .then(options_method_test)
       .then(form_data_test)
       .then(mode_credentials_test)
       .then(data_url_test)
       .then(function() { port.postMessage({results: 'finish'}); })
       .catch(function(e) { port.postMessage({results: 'failure:' + e}); });
   });
 </script>