Add flag for Intl BestFitMatcher

Make it ready to stage with harmony_intl_best_fit_matcher flag

Bug: v8:11584
Change-Id: Ia6b9057b94dabe2a1edbea6855e2c42759ae1d5f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2773796
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73586}

src/flags/flag-definitions.h

@@ -260,8 +260,9 @@ DEFINE_IMPLICATION(harmony_weak_refs_with_cleanup_some, harmony_weak_refs)
   V(harmony_import_assertions, "harmony import assertions")
 
 #ifdef V8_INTL_SUPPORT
-#define HARMONY_INPROGRESS(V) \
-  HARMONY_INPROGRESS_BASE(V)  \
+#define HARMONY_INPROGRESS(V)                             \
+  HARMONY_INPROGRESS_BASE(V)                              \
+  V(harmony_intl_best_fit_matcher, "Intl BestFitMatcher") \
   V(harmony_intl_displaynames_date_types, "Intl.DisplayNames date types")
 #else
 #define HARMONY_INPROGRESS(V) HARMONY_INPROGRESS_BASE(V)

src/init/bootstrapper.cc

@@ -4327,6 +4327,7 @@ EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_private_brand_checks)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_class_static_blocks)
 
 #ifdef V8_INTL_SUPPORT
+EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_intl_best_fit_matcher)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_intl_displaynames_date_types)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_intl_dateformat_day_period)
 #endif  // V8_INTL_SUPPORT

src/objects/intl-objects.cc

@@ -1599,10 +1599,6 @@ Handle<JSArray> CreateArrayFromList(Isolate* isolate,
   return array;
 }
 
-// To mitigate the risk of bestfit locale matcher, we first check in without
-// turnning it on.
-static bool implement_bestfit = false;
-
 // ECMA 402 9.2.9 SupportedLocales(availableLocales, requestedLocales, options)
 // https://tc39.github.io/ecma402/#sec-supportedlocales
 MaybeHandle<JSObject> SupportedLocales(
@@ -1627,7 +1623,8 @@ MaybeHandle<JSObject> SupportedLocales(
   // 3. If matcher is "best fit", then
   //    a. Let supportedLocales be BestFitSupportedLocales(availableLocales,
   //       requestedLocales).
-  if (matcher == Intl::MatcherOption::kBestFit && implement_bestfit) {
+  if (matcher == Intl::MatcherOption::kBestFit &&
+      FLAG_harmony_intl_best_fit_matcher) {
     supported_locales =
         BestFitSupportedLocales(isolate, available_locales, requested_locales);
   } else {
@@ -1884,7 +1881,8 @@ Maybe<Intl::ResolvedLocale> Intl::ResolveLocale(
     const std::vector<std::string>& requested_locales, MatcherOption matcher,
     const std::set<std::string>& relevant_extension_keys) {
   std::string locale;
-  if (matcher == Intl::MatcherOption::kBestFit && implement_bestfit) {
+  if (matcher == Intl::MatcherOption::kBestFit &&
+      FLAG_harmony_intl_best_fit_matcher) {
     locale = BestFitMatcher(isolate, available_locales, requested_locales);
   } else {
     locale = LookupMatcher(isolate, available_locales, requested_locales);