Replace assert_promise_rejects with upstream promise_rejects.

third_party/WebKit/LayoutTests/http/tests/push_messaging/resources/pushmessagedata-worker.js

 importScripts('../../serviceworker/resources/worker-testharness.js');
-importScripts('/resources/testharness-helpers.js');
 
 function createPushMessageData(data)
 {
     // The PushMessageData object does not expose a constructor, but we can get an object
     // initialized with our data by constructing a PushEvent.
     return new PushEvent('PushEvent', { data: data }).data;
 }
 
 test(function() {
     const textContents = 'Hello, world!';
@@ skipping 89 matching lines @@
     assert_throws(null, () => new PushMessageData(new ArrayBuffer(8)));
 
 }, 'PushMessageData should not be constructable.');
 
 test(function() {
     var s = "e\u0328"; // 'e' + COMBINING OGONEK
     var data = createPushMessageData(s);
     assert_equals(data.text(), s, 'String should not be NFC-normalized.');
 
 }, 'PushEventInit data is not normalized');