[date] Add ICU backend for timezone info behind a flag

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 7e0800b0d17f008b47db594a1a0a4ecf76e5ff1b..917ae218435dd469f80c6a999ea39e0db66adcb1 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -3645,6 +3645,7 @@ EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_class_fields)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_object_rest_spread)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_dynamic_import)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_template_escapes)
+EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(icu_timezone_data)
 
 void InstallPublicSymbol(Factory* factory, Handle<Context> native_context,
                          const char* name, Handle<Symbol> value) {
@@ -4335,6 +4336,7 @@ bool Genesis::InstallExperimentalNatives() {
 #ifdef V8_I18N_SUPPORT
   static const char* icu_case_mapping_natives[] = {nullptr};
   static const char* datetime_format_to_parts_natives[] = {nullptr};
+  static const char* icu_timezone_data_natives[] = {nullptr};
 #endif
   static const char* harmony_restrictive_generators_natives[] = {nullptr};
   static const char* harmony_trailing_commas_natives[] = {nullptr};