[intl] Fall back on an invalid default locale to "und"

src/js/i18n.js

 // Copyright 2013 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.
 
 // ECMAScript 402 API implementation.
 
 /**
  * Intl object is a single object that has some named properties,
  * all of which are constructors.
  */
@@ skipping 135 matching lines @@
 };
 
 /**
  * Caches default ICU locale.
  */
 var DEFAULT_ICU_LOCALE = UNDEFINED;
 
 function GetDefaultICULocaleJS() {
   if (IS_UNDEFINED(DEFAULT_ICU_LOCALE)) {
     DEFAULT_ICU_LOCALE = %GetDefaultICULocale();
+    // Check that this is a valid default, otherwise fall back to "en"
+    for (let service in AVAILABLE_LOCALES) {
+      if (IS_UNDEFINED(getAvailableLocalesOf(service)[DEFAULT_ICU_LOCALE])) {
+        DEFAULT_ICU_LOCALE = "en";

[jungshik at Google, 2017/01/19 19:16:22]

Hmm... I'm not sure of falling back to 'en'. How about 'und'? 

[Dan Ehrenberg, 2017/02/10 08:54:28]

Done.

+        break;
+      }
+    }
   }
   return DEFAULT_ICU_LOCALE;
 }
 
 /**
  * Unicode extension regular expression.
  */
 var UNICODE_EXTENSION_RE = UNDEFINED;
 
 function GetUnicodeExtensionRE() {
@@ skipping 125 matching lines @@
     matcher = TO_STRING(matcher);
     if (matcher !== 'lookup' && matcher !== 'best fit') {
       throw %make_range_error(kLocaleMatcher, matcher);
     }
   } else {
     matcher = 'best fit';
   }
 
   var requestedLocales = initializeLocaleList(locales);
 
-  // Cache these, they don't ever change per service.
-  if (IS_UNDEFINED(AVAILABLE_LOCALES[service])) {
-    AVAILABLE_LOCALES[service] = getAvailableLocalesOf(service);
-  }
+  var availableLocales = getAvailableLocalesOf(service);
 
   // Use either best fit or lookup algorithm to match locales.
   if (matcher === 'best fit') {
     return initializeLocaleList(bestFitSupportedLocalesOf(
-        requestedLocales, AVAILABLE_LOCALES[service]));
+        requestedLocales, availableLocales));
   }
 
   return initializeLocaleList(lookupSupportedLocalesOf(
-      requestedLocales, AVAILABLE_LOCALES[service]));
+      requestedLocales, availableLocales));
 }
 
 
 /**
  * Returns the subset of the provided BCP 47 language priority list for which
  * this service has a matching locale when using the BCP 47 Lookup algorithm.
  * Locales appear in the same order in the returned list as in the input list.
  */
 function lookupSupportedLocalesOf(requestedLocales, availableLocales) {
   var matchedLocales = new InternalArray();
@@ skipping 106 matching lines @@
 
 /**
  * Returns best matched supported locale and extension info using basic
  * lookup algorithm.
  */
 function lookupMatcher(service, requestedLocales) {
   if (IS_NULL(%regexp_internal_match(GetServiceRE(), service))) {
     throw %make_error(kWrongServiceType, service);
   }
 
-  // Cache these, they don't ever change per service.
-  if (IS_UNDEFINED(AVAILABLE_LOCALES[service])) {
-    AVAILABLE_LOCALES[service] = getAvailableLocalesOf(service);
-  }
+  var availableLocales = getAvailableLocalesOf(service);
 
   for (var i = 0; i < requestedLocales.length; ++i) {
     // Remove all extensions.
     var locale = %RegExpInternalReplace(
         GetAnyExtensionRE(), requestedLocales[i], '');
     do {
-      if (!IS_UNDEFINED(AVAILABLE_LOCALES[service][locale])) {
+      if (!IS_UNDEFINED(availableLocales[locale])) {
         // Return the resolved locale and extension.
         var extensionMatch = %regexp_internal_match(
             GetUnicodeExtensionRE(), requestedLocales[i]);
         var extension = IS_NULL(extensionMatch) ? '' : extensionMatch[0];
         return {'locale': locale, 'extension': extension, 'position': i};
       }
       // Truncate locale if possible.
       var pos = %StringLastIndexOf(locale, '-');
       if (pos === -1) {
         break;
@@ skipping 190 matching lines @@
 }
 
 
 /**
  * Returns an Object that contains all of supported locales for a given
  * service.
  * In addition to the supported locales we add xx-ZZ locale for each xx-Yyyy-ZZ
  * that is supported. This is required by the spec.
  */
 function getAvailableLocalesOf(service) {
+  // Cache these, they don't ever change per service.
+  if (!IS_UNDEFINED(AVAILABLE_LOCALES[service])) {
+    return AVAILABLE_LOCALES[service];
+  }
+
   var available = %AvailableLocalesOf(service);
 
   for (var i in available) {
     if (HAS_OWN_PROPERTY(available, i)) {
       var parts = %regexp_internal_match(
           /^([a-z]{2,3})-([A-Z][a-z]{3})-([A-Z]{2})$/, i);
       if (!IS_NULL(parts)) {
         // Build xx-ZZ. We don't care about the actual value,
         // as long it's not undefined.
         available[parts[1] + '-' + parts[3]] = null;
       }
     }
   }
 
+  AVAILABLE_LOCALES[service] = available;
+
   return available;
 }
 
 
 /**
  * Defines a property and sets writable and enumerable to true.
  * Configurable is false by default.
  */
 function defineWEProperty(object, property, value) {
   %object_define_property(object, property,
@@ skipping 1481 matching lines @@
   }
 );
 
 %FunctionRemovePrototype(FormatDateToParts);
 
 utils.Export(function(to) {
   to.FormatDateToParts = FormatDateToParts;
 });
 
 })