Upstream service worker "request" tests to WPT

third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/resources/request-body-blob-worker.js

 self.addEventListener('fetch', event => {
     if (event.request.url.indexOf('?post-with-blob-body') == -1)
       return;
     event.respondWith(event.request.text().then(body => {
         if (body.indexOf('it\'s me the blob') == -1)
           return new Response('fail');
         if (body.indexOf('and more blob!') == -1)
           return new Response('fail');
         return new Response('Pass');
       }));
   });