Add D8 flag --no-fail that ignores exceptions on exit.

The NumFuzz fuzzers need to make use of this flag to ignore
Mjsunit exceptions and other exceptions. The flag ignores
the exit code 1.

R=​clemensb@chromium.org
R=cbruni@chromium.org

Bug: v8:11826
Change-Id: Ic0878078edec7292e43cdb18dd6fb32f7bbad12c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3103310
Commit-Queue: Almothana Athamneh <almuthanna@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76376}

src/d8/d8.cc

@@ -4265,6 +4265,9 @@ bool Shell::SetOptions(int argc, char* argv[]) {
     } else if (strcmp(argv[i], "--throws") == 0) {
       options.expected_to_throw = true;
       argv[i] = nullptr;
+    } else if (strcmp(argv[i], "--no-fail") == 0) {
+      options.no_fail = true;
+      argv[i] = nullptr;
     } else if (strncmp(argv[i], "--icu-data-file=", 16) == 0) {
       options.icu_data_file = argv[i] + 16;
       argv[i] = nullptr;
@@ -4514,7 +4517,8 @@ int Shell::RunMain(Isolate* isolate, bool last_run) {
     Shell::unhandled_promise_rejections_.store(0);
   }
   // In order to finish successfully, success must be != expected_to_throw.
-  return success == Shell::options.expected_to_throw ? 1 : 0;
+  if (Shell::options.no_fail) return 0;
+  return (success == Shell::options.expected_to_throw ? 1 : 0);
 }
 
 void Shell::CollectGarbage(Isolate* isolate) {

src/d8/d8.h

@@ -385,6 +385,7 @@ class ShellOptions {
   DisallowReassignment<bool> interactive_shell = {"shell", false};
   bool test_shell = false;
   DisallowReassignment<bool> expected_to_throw = {"throws", false};
+  DisallowReassignment<bool> no_fail = {"no-fail", false};
   DisallowReassignment<bool> ignore_unhandled_promises = {
       "ignore-unhandled-promises", false};
   DisallowReassignment<bool> mock_arraybuffer_allocator = {

test/mjsunit/verify-no-fail.js

+// Copyright 2021 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: --no-fail
+
+assertTrue(false);