Allow trailing commas in function parameter lists

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index ec7c1bc4bbaba5d272aff14cf7ddfdff44b4c821..4e0647bf2a5a09408a14009d6a653b5a354364bc 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -2697,6 +2697,7 @@ EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(icu_case_mapping)
 #endif
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_async_await)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_restrictive_generators)
+EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_trailing_commas)
 
 void InstallPublicSymbol(Factory* factory, Handle<Context> native_context,
                          const char* name, Handle<Symbol> value) {
@@ -3275,6 +3276,7 @@ bool Genesis::InstallExperimentalNatives() {
   static const char* harmony_async_await_natives[] = {
       "native harmony-async-await.js", nullptr};
   static const char* harmony_restrictive_generators_natives[] = {nullptr};
+  static const char* harmony_trailing_commas_natives[] = {nullptr};
 
   for (int i = ExperimentalNatives::GetDebuggerCount();
        i < ExperimentalNatives::GetBuiltinsCount(); i++) {