Upstream foreign fetch tests.

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

 self.addEventListener('install', function(event) {
     test(function() {
         assert_throws(new TypeError(), function() {
             new ForeignFetchEvent('type');
           });
       }, 'ForeignFetchEvent constructor with no init dict');
 
     test(function() {
         assert_throws(new TypeError(), function() {
             new ForeignFetchEvent('type', {});
@@ skipping 10 matching lines @@
         var request = new Request('https://www.example.com/');
         var event = new ForeignFetchEvent('type', { request: request, origin: 'origin' });
         assert_equals(event.type, 'type');
         assert_equals(event.request, request);
         assert_equals(event.origin, 'origin');
       }, 'ForeignFetchEvent constructor with all init dict members');
   });
 
 // Import testharness after install handler to make sure our install handler
 // runs first. Otherwise only one test will run.
-importScripts('../../resources/testharness.js');
+importScripts('/resources/testharness.js');