Rename fetch layout tests.

LayoutTests/http/tests/fetch/resources/thorough-worker.js

 importScripts('fetch-test-options.js');
-importScripts('fetch-access-control-util.js');
+importScripts('thorough-util.js');
 
 var port = undefined;
 var isTestTargetFetch = false;
 
 self.onmessage = function(e) {
   var message = e.data;
   if ('port' in message) {
     port = message.port;
   } else if (message.msg === 'START TEST CASE') {
     isTestTargetFetch = true;
     port.postMessage({msg: 'READY'});
   }
 };
 
 self.addEventListener('fetch', function(event) {
     if (!isTestTargetFetch) {
       // Don't handle the event when it is not the test target fetch such as a
       // redirected fetch or for the iframe html.
       return;
     }
     isTestTargetFetch = false;
 
     event.respondWith(
       doFetch(event.request)
         .then(function(message) {
             var response = message.response;
             message.response = undefined;
-            // Send the result to fetch-access-control-util.js.
+            // Send the result to thorough-control-util.js.
             port.postMessage(message);
             return response;
           })
         .catch(function(message) {
             port.postMessage(message);
             return Promise.reject();
           })
       );
   });