[Intl] Fix getting undefined property crash

If the key of the u-ext has no value it will return error so
we should just return undefined for that case.

Bug: v8:8663
Change-Id: I7446ad74c8d0609ad268385b6f4d986060424ce9
Reviewed-on: https://chromium-review.googlesource.com/c/1404194
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58682}

src/objects/js-locale.cc

@@ -148,8 +148,7 @@ Handle<Object> UnicodeKeywordValue(Isolate* isolate, Handle<JSLocale> locale,
   UErrorCode status = U_ZERO_ERROR;
   std::string value =
       icu_locale->getUnicodeKeywordValue<std::string>(key, status);
-  CHECK(U_SUCCESS(status));
-  if (value == "") {
+  if (status == U_ILLEGAL_ARGUMENT_ERROR || value == "") {
     return isolate->factory()->undefined_value();
   }
   return isolate->factory()->NewStringFromAsciiChecked(value.c_str());

test/intl/locale/property.js

+// Copyright 2019 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: --harmony-locale
+
+// Make sure that accessing locale property will return undefined instead of
+// crash.
+
+let locale = new Intl.Locale('sr');
+
+assertEquals('sr', locale.toString());
+assertEquals('sr', locale.baseName);
+assertEquals('sr', locale.language);
+assertEquals(undefined, locale.script);
+assertEquals(undefined, locale.region);
+assertEquals(false, locale.numeric);
+assertEquals(undefined, locale.calendar);
+assertEquals(undefined, locale.collation);
+assertEquals(undefined, locale.hourCycle);
+assertEquals(undefined, locale.caseFirst);
+assertEquals(undefined, locale.numberingSystem);