Upstream foreign fetch tests.

third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/foreign-fetch-cors-worker.js

-importScripts('../../resources/get-host-info.js');
-var host_info = get_host_info();
-
-self.addEventListener('install', function(event) {
-    event.registerForeignFetch({scopes: [registration.scope], origins: ['*']});
-  });
-
-self.addEventListener('foreignfetch', function(event) {
-    var response = JSON.parse(decodeURIComponent(location.search.substring(1)));
-    var url = new URL(event.request.url);
-    var params = JSON.parse(decodeURIComponent(url.search.substring(1)));
-    var url_to_fetch = 'fetch-access-control.php?';
-    if (params.cross_origin) {
-      url_to_fetch =
-          host_info.HTTPS_ORIGIN + '/serviceworker/resources/' + url_to_fetch;
-    }
-    if (params.with_aceheaders)
-      url_to_fetch += 'ACEHeaders=X-ServiceWorker-ServerHeader&';
-    if (params.with_acaorigin)
-      url_to_fetch += 'ACAOrigin=*';
-    fetch_params = {};
-    if (params.cross_origin && !params.with_acaorigin)
-       fetch_params.mode = 'no-cors';
-    event.respondWith(fetch(url_to_fetch, fetch_params)
-      .then(r => {
-          response.response = r;
-          return response;
-        }));
-    return;
-  });