Reland "[intl] Improve test coverage of "best fit" localeMatcher"

This is a reland of dd8845cd74

Original change's description:
> [intl] Improve test coverage of "best fit" localeMatcher
>
> https: //docs.google.com/document/d/1cPGfiihn76yj2iAomKcspPFyLLcnk3WkCiqceBQPQyk/edit#heading=h.cc9tt7s0iwsd
> Bug: v8:7051
> Change-Id: I8c35e859062c5bdb009334dd1b725751e6df2123
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2965481
> Reviewed-by: Shu-yu Guo <syg@chromium.org>
> Commit-Queue: Frank Tang <ftang@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#75228}

Bug: v8:7051
Change-Id: I9af13b8fdf7ec3de2ac24050074d13fcdef981c7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2973648
Reviewed-by: Frank Tang <ftang@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75280}

test/intl/localematcher/bestfit-known-locales.js

@@ -0,0 +1,39 @@
+// 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: --harmony_intl_best_fit_matcher
+//
+// Test the supportedLocales and resolvedOptions handle "zh-TW", "zh-Hant-TW",
+// etc.
+
+const intlObjs = [
+    Intl.Collator,
+    Intl.DateTimeFormat,
+    Intl.DisplayNames,
+    Intl.ListFormat,
+    Intl.NumberFormat,
+    Intl.PluralRules,
+    Intl.RelativeTimeFormat,
+    Intl.Segmenter,
+];
+
+let bestFitOpt = {localeMatcher: "best fit"};
+let defaultLocale = (new Intl.NumberFormat()).resolvedOptions().locale;
+intlObjs.forEach(function(obj) {
+  [{}, bestFitOpt].forEach(function(opt) {
+    // Test consistent between "zh-TW" and "zh-Hant-TW". Either both are
+    // supported or neither are supported.
+    assertEquals((obj.supportedLocalesOf(["zh-TW"], opt)).length,
+                 (obj.supportedLocalesOf(["zh-Hant-TW"], opt)).length);
+    assertEquals((obj.supportedLocalesOf(["zh-MO"], opt)).length,
+                 (obj.supportedLocalesOf(["zh-Hant-MO"], opt)).length);
+    assertEquals((obj.supportedLocalesOf(["zh-HK"], opt)).length,
+                 (obj.supportedLocalesOf(["zh-Hant-HK"], opt)).length);
+    assertEquals((obj.supportedLocalesOf(["zh-CN"], opt)).length,
+                 (obj.supportedLocalesOf(["zh-Hans-CN"], opt)).length);
+    assertEquals((obj.supportedLocalesOf(["zh-SG"], opt)).length,
+                 (obj.supportedLocalesOf(["zh-Hans-SG"], opt)).length);
+  });
+
+});

test/intl/localematcher/bestfit-macrolanguages.js

@@ -0,0 +1,56 @@
+// 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: --harmony_intl_best_fit_matcher
+//
+// Test the supportedLocales and resolvedOptions handle macrolanguages
+// documented in https://unicode.org/reports/tr35/#Field_Definitions
+
+const intlObjs = [
+    Intl.Collator,
+    Intl.DateTimeFormat,
+    Intl.DisplayNames,
+    Intl.ListFormat,
+    Intl.NumberFormat,
+    Intl.PluralRules,
+    Intl.RelativeTimeFormat,
+    Intl.Segmenter,
+];
+
+// Macrolanguages in
+// https://unicode.org/reports/tr35/#Field_Definitionsk
+const macroLanguageMap = {
+  'cmn': 'zh',
+  'arb': 'ar',
+  'zsm': 'ms',
+  'swh': 'sw',
+  'uzn': 'uz',
+//  'knn': 'kok',  // chrome does not ship data for kok locale
+  'kmr': 'ku',
+};
+
+let bestFitOpt = {localeMatcher: "best fit"};
+let defaultLocale = (new Intl.NumberFormat()).resolvedOptions().locale;
+intlObjs.forEach(function(obj) {
+  for (const [macro, lang] of Object.entries(macroLanguageMap)) {
+    const justMacro = [macro];
+    // Test the macro language will be persist in the supportedLocalesOf
+    assertEquals([lang], obj.supportedLocalesOf(justMacro));
+    assertEquals([lang], obj.supportedLocalesOf(justMacro, bestFitOpt));
+
+    // Test the macro language would be resolved to a locale other than the
+    // default locale.
+    if (obj == Intl.DisplayNames) {
+      assertTrue(defaultLocale != (new obj(macro, {type: "language"}))
+        .resolvedOptions().locale);
+      assertTrue(defaultLocale !=
+          (new obj(macro, {type: "language", localeMatcher: "best fit"}))
+          .resolvedOptions().locale);
+    } else {
+      assertTrue(defaultLocale != (new obj(macro)).resolvedOptions().locale);
+      assertTrue(defaultLocale != (new obj(macro, bestFitOpt))
+          .resolvedOptions().locale);
+    }
+  }
+});

test/intl/localematcher/bestfit-supplemental-files.js

@@ -0,0 +1,46 @@
+// 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: --harmony_intl_best_fit_matcher
+//
+// Test the supportedLocales and resolvedOptions based on
+// https://github.com/unicode-org/cldr/blob/master/common/supplemental/languageInfo.xml
+
+const intlObjs = [
+    Intl.Collator,
+    Intl.DateTimeFormat,
+    Intl.DisplayNames,
+    Intl.ListFormat,
+    Intl.NumberFormat,
+    Intl.RelativeTimeFormat,
+    Intl.PluralRules,
+    Intl.Segmenter,
+];
+
+
+function verifyResolvedLocale(obj, opt, l1, l2) {
+  let options = {}
+  options = Object.assign(options, opt);
+  if (obj == Intl.DisplayNames) {
+    options['type'] = "language";
+  }
+  let resolvedLocale = (new obj(l1, options)).resolvedOptions().locale;
+  assertTrue((l1 == resolvedLocale) ||
+             (l2 == resolvedLocale.substring(0, l2.length)));
+}
+
+let bestFitOpt = {localeMatcher: "best fit"};
+let defaultLocale = (new Intl.NumberFormat()).resolvedOptions().locale;
+intlObjs.forEach(function(obj) {
+  [{}, bestFitOpt].forEach(function(opt) {
+    print(obj);
+    verifyResolvedLocale(obj, opt, "co", "fr");
+    verifyResolvedLocale(obj, opt, "crs", "fr");
+    verifyResolvedLocale(obj, opt, "lb", "de");
+    verifyResolvedLocale(obj, opt, "gsw", "de");
+    verifyResolvedLocale(obj, opt, "btj", "ms");
+    verifyResolvedLocale(obj, opt, "bjn", "ms");
+  });
+
+});

test/intl/localematcher/bestfit-supportedLocalesOf-subset.js

@@ -22,5 +22,17 @@ function verifySupportedLocalesAreSubarray(f, ll) {
   assertSubarray(f(ll), ll);
 }
 
-verifySupportedLocalesAreSubarray(Intl.DateTimeFormat.supportedLocalesOf, ['en', 'ceb']);
-verifySupportedLocalesAreSubarray(Intl.DateTimeFormat.supportedLocalesOf, ['en', 'ceb', 'fil']);
+const intlObjs = [
+    Intl.Collator,
+    Intl.DateTimeFormat,
+    Intl.DisplayNames,
+    Intl.ListFormat,
+    Intl.NumberFormat,
+    Intl.PluralRules,
+    Intl.RelativeTimeFormat,
+    Intl.Segmenter,
+];
+intlObjs.forEach(function(obj) {
+  verifySupportedLocalesAreSubarray(obj.supportedLocalesOf, ['en', 'ceb']);
+  verifySupportedLocalesAreSubarray(obj.supportedLocalesOf, ['en', 'ceb', 'fil']);
+});