Implement new Function.prototype.toString and fix CreateDynamicFunction parsing

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 4c34c0fa27331989fe51e3ed0b8fd150eb996955..3bfc0c76460bab3b6d5672c81a987c2c0f2ab8e6 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -3246,6 +3246,7 @@ EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(icu_case_mapping)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_async_await)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_restrictive_generators)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_trailing_commas)
+EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_function_tostring)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_class_fields)
 
 void InstallPublicSymbol(Factory* factory, Handle<Context> native_context,
@@ -3844,6 +3845,7 @@ bool Genesis::InstallExperimentalNatives() {
   static const char* harmony_async_await_natives[] = {nullptr};
   static const char* harmony_restrictive_generators_natives[] = {nullptr};
   static const char* harmony_trailing_commas_natives[] = {nullptr};
+  static const char* harmony_function_tostring_natives[] = {nullptr};
   static const char* harmony_class_fields_natives[] = {nullptr};
 
   for (int i = ExperimentalNatives::GetDebuggerCount();