Allow ICU to normalize time zones

There's at least one case of a time zone alias: Asia/Kathmandu aliases
Asia/Katmandu. ICU seems to normalize to the (deprecated) latter choice.
V8 internationalization choked on this change; this patch interprets
ICU's output more precisely and allows it.

BUG=chromium:487322
R=jungshik,adamk
LOG=Y

Review URL: https://codereview.chromium.org/1509273007

Cr-Commit-Position: refs/heads/master@{#32769}

src/js/i18n.js

@@ -1574,7 +1574,7 @@ function initializeDateTimeFormat(dateFormat, locales, options) {
   var formatter = %CreateDateTimeFormat(
     requestedLocale, {skeleton: ldmlString, timeZone: tz}, resolved);
 
-  if (!IS_UNDEFINED(tz) && tz !== resolved.timeZone) {
+  if (resolved.timeZone === "Etc/Unknown") {
     throw MakeRangeError(kUnsupportedTimeZone, tz);
   }
 

test/mjsunit/regress/regress-487322.js

+// Copyright 2015 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.
+
+// Normalizes Kat{h,}mandu (chromium:487322)
+df = new Intl.DateTimeFormat('en-US', {'timeZone': 'Asia/Katmandu'})
+assertEquals('Asia/Katmandu', df.resolvedOptions().timeZone);
+
+df = new Intl.DateTimeFormat('en-US', {'timeZone': 'Asia/Kathmandu'})
+assertEquals('Asia/Katmandu', df.resolvedOptions().timeZone);
+
+// Throws for unsupported time zones.
+assertThrows(() => Intl.DateTimeFormat(undefined, {timeZone: 'Aurope/Paris'}));