Add optional types to function/method declarations

src/parsing/preparser.h

Index: src/parsing/preparser.h
diff --git a/src/parsing/preparser.h b/src/parsing/preparser.h
index 8ccba7373adbaac9370257322b975128f2885387..2051ab100f3948a30c5925020bef9bd133f6753f 100644
--- a/src/parsing/preparser.h
+++ b/src/parsing/preparser.h
@@ -1200,7 +1200,7 @@ class PreParserTraits {
       PreParserIdentifier name, Scanner::Location function_name_location,
       FunctionNameValidity function_name_validity, FunctionKind kind,
       int function_token_position, FunctionLiteral::FunctionType type,
-      LanguageMode language_mode, bool* ok);
+      LanguageMode language_mode, typesystem::TypeFlags type_flags, bool* ok);
 
   PreParserExpression ParseClassLiteral(PreParserIdentifier name,
                                         Scanner::Location class_name_location,
@@ -1378,11 +1378,13 @@ class PreParser : public ParserBase<PreParserTraits> {
       const PreParserFormalParameters& parameters, FunctionKind kind,
       FunctionLiteral::FunctionType function_type, bool* ok);
 
-  Expression ParseFunctionLiteral(
-      Identifier name, Scanner::Location function_name_location,
-      FunctionNameValidity function_name_validity, FunctionKind kind,
-      int function_token_pos, FunctionLiteral::FunctionType function_type,
-      LanguageMode language_mode, bool* ok);
+  Expression ParseFunctionLiteral(Identifier name,
+                                  Scanner::Location function_name_location,
+                                  FunctionNameValidity function_name_validity,
+                                  FunctionKind kind, int function_token_pos,
+                                  FunctionLiteral::FunctionType function_type,
+                                  LanguageMode language_mode,
+                                  typesystem::TypeFlags type_flags, bool* ok);
   void ParseLazyFunctionLiteralBody(bool* ok,
                                     Scanner::BookmarkScope* bookmark = nullptr);