Rewrite Fetch API referrer layout tests with service worker

third_party/WebKit/LayoutTests/http/tests/fetch/resources/fetch-test-helpers.js

 if (self.importScripts) {
   importScripts('/resources/testharness.js');
   importScripts('/serviceworker/resources/test-helpers.js');
   importScripts('/fetch/resources/fetch-test-options.js');
 }
 
 function getContentType(headers) {
   var content_type = '';
   for (var header of headers) {
     if (header[0] == 'content-type')
@@ skipping 198 matching lines @@
                   if (mode !== 'same-origin') {
                     assert_unreached(
                       'Test 5: Cross-origin HTTPS request must success: ' +
                       'mode = ' + mode);
                   }
                 });
           });
     }, 'Block fetch() as mixed content (' + mode + ')');
 }
 
-function add_referrer_tests(tests) {
+function add_referrer_tests(tests, global) {
+  global = global || self;
   for (let test of tests) {
     let url = test[0];
     let referrer = test[1];
     let policy = test[2];
     let expected = test[3];
     promise_test(t => {
         var request = new Request(url,
           {referrer: referrer, referrerPolicy: policy, mode: 'cors'});
-        return fetch(new Request(url, request)).then(res => {
+        return global.fetch(new Request(url, request)).then(res => {
             return res.json();
           }).then(json => {
             assert_equals(json.referrer, expected, 'referrer');
           });
      },
      `referrer test: url = ${url}, referrer = ${referrer}, policy = ${policy}`);
   }
 }