[es7] implement exponentiation operator proposal

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index fa72f425c442cc313babf527170c3dae31107581..95786f58ceac8cd3ecd4441d5f4dbcfc8999eb2e 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -2277,6 +2277,7 @@ 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_restrictive_declarations)
+EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_exponentiation_operator)
 
 void InstallPublicSymbol(Factory* factory, Handle<Context> native_context,
                          const char* name, Handle<Symbol> value) {
@@ -2980,6 +2981,7 @@ bool Genesis::InstallExperimentalNatives() {
   static const char* harmony_object_own_property_descriptors_natives[] = {
       nullptr};
   static const char* harmony_array_prototype_values_natives[] = {nullptr};
+  static const char* harmony_exponentiation_operator_natives[] = {nullptr};
 
   for (int i = ExperimentalNatives::GetDebuggerCount();
        i < ExperimentalNatives::GetBuiltinsCount(); i++) {