Bug 1736317 [wpt PR 31293] - Streams: remove WritableStreamDefaultController.abortReason asserts in tests, a=testonly

Automatic update from web-platform-tests
Streams: remove abortReason asserts in tests

Follows whatwg/streams#1177.
--

wpt-commits: a43ea460b71db5a4692cbcd896d0f9ad844bc60c
wpt-pr: 31293

Author: nidhijaju

testing/web-platform/tests/streams/writable-streams/aborting.any.js

@@ -1384,10 +1384,8 @@ test(t => {
 
   assert_true(ctrl.signal instanceof AbortSignal);
   assert_false(ctrl.signal.aborted);
-  assert_equals(ctrl.abortReason, undefined);
   ws.abort(e);
   assert_true(ctrl.signal.aborted);
-  assert_equals(ctrl.abortReason, e);
 }, 'WritableStreamDefaultController.signal');
 
 promise_test(async t => {
@@ -1405,10 +1403,8 @@ promise_test(async t => {
   await called;
 
   assert_false(ctrl.signal.aborted);
-  assert_equals(ctrl.abortReason, undefined);
   writer.abort();
   assert_true(ctrl.signal.aborted);
-  assert_equals(ctrl.abortReason, undefined);
 }, 'the abort signal is signalled synchronously - write');
 
 promise_test(async t => {