Remove --harmony-modules flag and let embedder decide when modules are used

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index fa72f425c442cc313babf527170c3dae31107581..f40f94d51e20eb52d3ff62961de6749257bbc6a0 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -2260,7 +2260,6 @@ void Bootstrapper::ExportExperimentalFromRuntime(Isolate* isolate,
 #define EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(id) \
   void Genesis::InitializeGlobal_##id() {}
 
-EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_modules)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_sloppy)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_sloppy_function)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_sloppy_let)
@@ -2946,7 +2945,6 @@ bool Genesis::InstallNatives(GlobalContextType context_type) {
 
 bool Genesis::InstallExperimentalNatives() {
   static const char* harmony_proxies_natives[] = {"native proxy.js", nullptr};
-  static const char* harmony_modules_natives[] = {nullptr};
   static const char* harmony_regexps_natives[] = {"native harmony-regexp.js",
                                                   nullptr};
   static const char* harmony_iterator_close_natives[] = {nullptr};