Remove unused code in serviceworkercontainer-interface test

Change-Id: I29fce7fafe5ab0923eed465fb58fcf5def079689
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1355195Reviewed-by: Erik Luo <luoe@chromium.org>
Commit-Queue: Connor Clark <cjamcl@google.com>
Cr-Commit-Position: refs/heads/master@{#667244}

third_party/blink/web_tests/fast/serviceworker/serviceworkercontainer-interface.html

@@ -2,13 +2,6 @@
 <script src="../../resources/testharness.js"></script>
 <script src="../../resources/testharnessreport.js"></script>
 <script>
-function getPropertyDescriptor(name) {
-  return (
-      Object.getOwnPropertyDescriptor(ServiceWorkerContainer.prototype, name) ||
-      // FIXME: Remove this when http://crbug.com/43394 is fixed.
-      Object.getOwnPropertyDescriptor(navigator.serviceWorker, name));
-}
-
 test(function() {
   assert_true('ServiceWorkerContainer' in window,
               'the constructor should be defined');