Upstream foreign fetch tests.

third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/resources/foreign-fetch-worker.js

 self.addEventListener('install', function(event) {
     var params = JSON.parse(decodeURIComponent(location.search.substring(1)));
     if (!('scopes' in params)) {
       if ('relscopes' in params) {
         params.scopes = params.relscopes.map(s => registration.scope + s);
       } else {
         params.scopes = [registration.scope];
       }
     }
     if (!('origins' in params))
@@ skipping 58 matching lines @@
       }
     }
 
     if (handler) {
       handler.fn(event);
     } else {
       event.respondWith({origin: event.origin,
                          response: new Response('unexpected request')});
     }
   });