Fix Use-of-uninitialized-value

v8::internal::JSDateTimeFormat::New

Bug: chromium:1177812, chromium:1177623
Change-Id: I91e6babd796c6735e96e3cd1541d8aba51aaefee
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2706353
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72878}

src/objects/js-date-time-format.cc

@@ -437,7 +437,7 @@ std::string CanonicalizeTimeZoneID(const std::string& input) {
         title[1] = 'S';
       }
       return title;
-    } else if (memcmp(upper.c_str(), "SYSTEMV/", 8) == 0) {
+    } else if (strncmp(upper.c_str(), "SYSTEMV/", 8) == 0) {
       upper.replace(0, 8, "SystemV/");
       return upper;
     }

test/intl/regress-1177623.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.
+
+assertEquals("UTC", Intl.DateTimeFormat('en', { timeZone: 'Zulu' }).resolvedOptions().timeZone);

test/intl/regress-1177812.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.
+
+for (let tz of [ false, [], {}, function () {}]) {
+  assertThrows(() => new Date().toLocaleString(undefined, { timeZone: tz }), RangeError);
+}