Upstream service worker "XHR" test to WPT

third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/resources/fetch-request-xhr-sync-worker.js

+'use strict';
+
+self.onfetch = function(event) {
+  if (event.request.url.indexOf('fetch-request-xhr-sync-data.txt') !== -1) {
+    event.respondWith(new Response('hello'));

[falken, 2017/05/30 01:08:41]

how about changing this string to 'PASS'

[mike3, 2017/05/30 14:48:15]

It probably doesn't matter as much given the change of assertion, but I've used
the value 'Response from service worker' to make this even more explicit.

+  }
+};