[es7] implement exponentiation operator proposal

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 6301515022531aab9ff3ec299eb4ab89d684a950..9e6a5257f55b20adad8af659ec5a1030fb70fde4 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -2349,6 +2349,7 @@ EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_function_sent)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(promise_extra)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_tailcalls)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_instanceof)
+EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_exponentiation_operator)
 
 void InstallPublicSymbol(Factory* factory, Handle<Context> native_context,
                          const char* name, Handle<Symbol> value) {
@@ -3011,6 +3012,7 @@ bool Genesis::InstallExperimentalNatives() {
   static const char* harmony_object_values_entries_natives[] = {nullptr};
   static const char* harmony_object_own_property_descriptors_natives[] = {
       nullptr};
+  static const char* harmony_exponentiation_operator_natives[] = {nullptr};
 
   for (int i = ExperimentalNatives::GetDebuggerCount();
        i < ExperimentalNatives::GetBuiltinsCount(); i++) {