Ignore unhandled promises in one more test

This is a follow-up to https://crrev.com/c/2238569.

R=cbruni@chromium.org

No-Try: true
Bug: v8:10556
Change-Id: Id667359a3098bf6e248716d33a8fcfc110236bb8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2262916Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68504}

test/mjsunit/regress/wasm/regress-712569.js

 // Copyright 2017 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-//
+
+// Flags: --ignore-unhandled-promises
 
 var v11 = {};
 Object.defineProperty(v11.__proto__, 0, {