Expose getCanonicalLocales() for Intl object

src/runtime/runtime-i18n.cc

 // Copyright 2014 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.
 
 
 #ifdef V8_I18N_SUPPORT
 #include "src/runtime/runtime-utils.h"
 
 #include <memory>
 
@@ skipping 45 matching lines @@
       CopyChars(dest->get(), flat.ToOneByteVector().start(), length);
     }
     return reinterpret_cast<const UChar*>(dest->get());
   } else {
     return reinterpret_cast<const UChar*>(flat.ToUC16Vector().start());
   }
 }
 
 }  // namespace
 
+// ECMA 402 6.2.3
 RUNTIME_FUNCTION(Runtime_CanonicalizeLanguageTag) {
   HandleScope scope(isolate);
   Factory* factory = isolate->factory();
 
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(String, locale_id_str, 0);
 
   v8::String::Utf8Value locale_id(v8::Utils::ToLocal(locale_id_str));
 
   // Return value which denotes invalid language tag.
+  // TODO(jshin): Can uloc_{for,to}TanguageTag fail even for structually valid
+  // language tags? If not, just add CHECK instead of returning 'invalid-tag'.
   const char* const kInvalidTag = "invalid-tag";
 
   UErrorCode error = U_ZERO_ERROR;
   char icu_result[ULOC_FULLNAME_CAPACITY];
   int icu_length = 0;
 
   uloc_forLanguageTag(*locale_id, icu_result, ULOC_FULLNAME_CAPACITY,
                       &icu_length, &error);
   if (U_FAILURE(error) || icu_length == 0) {
     return *factory->NewStringFromAsciiChecked(kInvalidTag);
@@ skipping 1065 matching lines @@
   Handle<FixedArray> date_cache_version =
       Handle<FixedArray>::cast(isolate->eternal_handles()->GetSingleton(
           EternalHandles::DATE_CACHE_VERSION));
   return date_cache_version->get(0);
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_I18N_SUPPORT