ServiceWorker: remove get_newest_worker() helper (cleanup)

LayoutTests/http/tests/serviceworker/resources/test-helpers.js

Index: LayoutTests/http/tests/serviceworker/resources/test-helpers.js
diff --git a/LayoutTests/http/tests/serviceworker/resources/test-helpers.js b/LayoutTests/http/tests/serviceworker/resources/test-helpers.js
index e3a0a883f2818fd675e18b91d0edf88b4135f269..7885556f66cb3c56ff02159ff8f22a26c4fadb6c 100644
--- a/LayoutTests/http/tests/serviceworker/resources/test-helpers.js
+++ b/LayoutTests/http/tests/serviceworker/resources/test-helpers.js
@@ -66,21 +66,6 @@ function normalizeURL(url) {
   return new URL(url, document.location).toString().replace(/#.*$/, '');
 }
 
-function get_newest_worker(registration) {
-  if (!registration) {
-    return Promise.reject(new Error(
-      'get_newest_worker must be passed a ServiceWorkerRegistration'));
-  }
-  if (registration.installing)
-    return Promise.resolve(registration.installing);
-  if (registration.waiting)
-    return Promise.resolve(registration.waiting);
-  if (registration.active)
-    return Promise.resolve(registration.active);
-  return Promise.reject(new Error(
-    'registration must have at least one version'));
-}
-
 function wait_for_update(test, registration) {
   if (!registration || registration.unregister == undefined) {
     return Promise.reject(new Error(