[AST] Add method to concatenate AstRawStrings

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index e1f42787a012e095a8d29724bf25041ea7c75aa9..11309fe38bdaf90eb719da753ed850cca85ed81b 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -2806,6 +2806,7 @@ 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_class_fields)
+EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_private_class_fields)
 
 void InstallPublicSymbol(Factory* factory, Handle<Context> native_context,
                          const char* name, Handle<Symbol> value) {
@@ -3398,6 +3399,7 @@ bool Genesis::InstallExperimentalNatives() {
   static const char* harmony_restrictive_generators_natives[] = {nullptr};
   static const char* harmony_trailing_commas_natives[] = {nullptr};
   static const char* harmony_class_fields_natives[] = {nullptr};
+  static const char* harmony_private_class_fields_natives[] = {nullptr};
 
   for (int i = ExperimentalNatives::GetDebuggerCount();
        i < ExperimentalNatives::GetBuiltinsCount(); i++) {