Remove --harmony-for-in flag which is always false

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 74f2b2926c08f93e87c22044913e1156517f110b..52059757dcd7cce134ddbd722f86ef2cd20ac59d 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -3040,7 +3040,6 @@ void Bootstrapper::ExportExperimentalFromRuntime(Isolate* isolate,
   void Genesis::InitializeGlobal_##id() {}
 
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_do_expressions)
-EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_for_in)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_regexp_lookbehind)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_regexp_named_captures)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_regexp_property)
@@ -3633,7 +3632,6 @@ bool Genesis::InstallExperimentalNatives() {
   static const char* harmony_simd_natives[] = {"native harmony-simd.js",
                                                nullptr};
   static const char* harmony_do_expressions_natives[] = {nullptr};
-  static const char* harmony_for_in_natives[] = {nullptr};
   static const char* harmony_regexp_lookbehind_natives[] = {nullptr};
   static const char* harmony_restrictive_declarations_natives[] = {nullptr};
   static const char* harmony_regexp_named_captures_natives[] = {nullptr};