Import w3c tests for the service workers

third_party/WebKit/LayoutTests/imported/wpt/service-workers/service-worker/resources/fetch-request-no-freshness-headers-worker.js

 var requests = [];
 
 self.addEventListener('message', function(event) {
     event.data.port.postMessage({requests: requests});
   });
 
 self.addEventListener('fetch', function(event) {
     var url = event.request.url;
     var headers = [];
     for (var header of event.request.headers) {
       headers.push(header);
     }
     requests.push({
         url: url,
         headers: headers
       });
     event.respondWith(fetch(event.request));
   });