Upstream service worker `fetch` test to WPT

third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/fetch-request-css-cross-origin-mime-check-worker.js

-importScripts('../../resources/get-host-info.js');
-importScripts('test-helpers.js');
-
-self.addEventListener('fetch', function(event) {
-    if (event.request.url.indexOf('cross-origin-css.css') != -1) {
-      event.respondWith(fetch(
-          get_host_info()['HTTP_REMOTE_ORIGIN'] + base_path() +
-          'fetch-request-css-cross-origin-mime-check-cross.css',
-          {mode: 'no-cors'}));
-    } else if (event.request.url.indexOf('cross-origin-html.css') != -1) {
-      event.respondWith(fetch(
-          get_host_info()['HTTP_REMOTE_ORIGIN'] + base_path() +
-          'fetch-request-css-cross-origin-mime-check-cross.html',
-          {mode: 'no-cors'}));
-    } else if (event.request.url.indexOf('synthetic.css') != -1) {
-      event.respondWith(new Response("#synthetic { color: blue; }"));
-    } else {
-      event.respondWith(fetch(event.request));
-    }
-  });