[intl] Return "UTC" instead of "Etc/UTC" or "Etc/GMT" as DefaultTimeZone

Bug: v8:13112
Change-Id: I84e025e889fa3a0e5a52cc3ca986935ebe4b0c62
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3868712Reviewed-by: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83010}

src/objects/intl-objects.cc

@@ -2829,11 +2829,8 @@ MaybeHandle<String> Intl::CanonicalizeTimeZoneName(Isolate* isolate,
   icu::UnicodeString canonical;
   icu::TimeZone::getCanonicalID(time_zone_ustring, canonical, status);
   CHECK(U_SUCCESS(status));
-  if (canonical == UNICODE_STRING_SIMPLE("Etc/UTC") ||
-      canonical == UNICODE_STRING_SIMPLE("Etc/GMT")) {
-    return isolate->factory()->UTC_string();
-  }
-  return Intl::ToString(isolate, canonical);
+
+  return JSDateTimeFormat::TimeZoneIdToString(isolate, canonical);
 }
 
 bool Intl::IsValidTimeZoneName(Isolate* isolate, Handle<String> id) {
@@ -2951,7 +2948,8 @@ Handle<String> Intl::DefaultTimeZone(Isolate* isolate) {
   icu::UnicodeString canonical;
   icu::TimeZone::getCanonicalID(id, canonical, status);
   DCHECK(U_SUCCESS(status));
-  return Intl::ToString(isolate, canonical).ToHandleChecked();
+  return JSDateTimeFormat::TimeZoneIdToString(isolate, canonical)
+      .ToHandleChecked();
 }
 
 namespace {

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

@@ -492,9 +492,23 @@ int FractionalSecondDigitsFromPattern(const std::string& pattern) {
   }
   return result;
 }
-
 }  // namespace
 
+MaybeHandle<String> JSDateTimeFormat::TimeZoneIdToString(
+    Isolate* isolate, const icu::UnicodeString& id) {
+  // In CLDR (http://unicode.org/cldr/trac/ticket/9943), Etc/UTC is made
+  // a separate timezone ID from Etc/GMT even though they're still the same
+  // timezone. We have Etc/UTC because 'UTC', 'Etc/Universal',
+  // 'Etc/Zulu' and others are turned to 'Etc/UTC' by ICU. Etc/GMT comes
+  // from Etc/GMT0, Etc/GMT+0, Etc/GMT-0, Etc/Greenwich.
+  // ecma402#sec-canonicalizetimezonename step 3
+  if (id == UNICODE_STRING_SIMPLE("Etc/UTC") ||
+      id == UNICODE_STRING_SIMPLE("Etc/GMT")) {
+    return isolate->factory()->UTC_string();
+  }
+  return Intl::ToString(isolate, id);
+}
+
 Handle<Object> JSDateTimeFormat::TimeZoneId(Isolate* isolate,
                                             const icu::TimeZone& tz) {
   Factory* factory = isolate->factory();
@@ -503,26 +517,14 @@ Handle<Object> JSDateTimeFormat::TimeZoneId(Isolate* isolate,
   UErrorCode status = U_ZERO_ERROR;
   icu::UnicodeString canonical_time_zone;
   icu::TimeZone::getCanonicalID(time_zone, canonical_time_zone, status);
-  Handle<Object> timezone_value;
-  if (U_SUCCESS(status)) {
-    // In CLDR (http://unicode.org/cldr/trac/ticket/9943), Etc/UTC is made
-    // a separate timezone ID from Etc/GMT even though they're still the same
-    // timezone. We have Etc/UTC because 'UTC', 'Etc/Universal',
-    // 'Etc/Zulu' and others are turned to 'Etc/UTC' by ICU. Etc/GMT comes
-    // from Etc/GMT0, Etc/GMT+0, Etc/GMT-0, Etc/Greenwich.
-    // ecma402#sec-canonicalizetimezonename step 3
-    if (canonical_time_zone == UNICODE_STRING_SIMPLE("Etc/UTC") ||
-        canonical_time_zone == UNICODE_STRING_SIMPLE("Etc/GMT")) {
-      timezone_value = factory->UTC_string();
-    } else {
-      ASSIGN_RETURN_ON_EXCEPTION_VALUE(
-          isolate, timezone_value, Intl::ToString(isolate, canonical_time_zone),
-          Handle<Object>());
-    }
-  } else {
+  if (U_FAILURE(status)) {
     // Somehow on Windows we will reach here.
-    timezone_value = factory->undefined_value();
+    return factory->undefined_value();
   }
+  Handle<String> timezone_value;
+  ASSIGN_RETURN_ON_EXCEPTION_VALUE(
+      isolate, timezone_value, TimeZoneIdToString(isolate, canonical_time_zone),
+      Handle<Object>());
   return timezone_value;
 }
 

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

@@ -100,6 +100,9 @@ class JSDateTimeFormat
   V8_EXPORT_PRIVATE static const std::set<std::string>& GetAvailableLocales();
 
   Handle<Object> static TimeZoneId(Isolate* isolate, const icu::TimeZone& tz);
+  V8_WARN_UNUSED_RESULT static MaybeHandle<String> TimeZoneIdToString(
+      Isolate* isolate, const icu::UnicodeString& id);
+
   std::unique_ptr<icu::TimeZone> static CreateTimeZone(const char* timezone);
 
   V8_EXPORT_PRIVATE static std::string CanonicalizeTimeZoneID(