Import w3c tests for the service workers

third_party/WebKit/LayoutTests/imported/wpt/service-workers/service-worker/resources/invalid-blobtype-worker.js

 self.addEventListener('fetch', function(event) {
     var url = event.request.url;
     if (url.indexOf('dummy?test') == -1) {
       return;
     }
     event.respondWith(new Promise(function(resolve) {
-        var headers = new Headers;
         // null byte in blob type
         resolve(new Response(new Blob([],{type: 'a\0b'})));
       }));
   });