Implement ES2015 labelled function declaration restrictions

src/parsing/preparser.h

Index: src/parsing/preparser.h
diff --git a/src/parsing/preparser.h b/src/parsing/preparser.h
index 3afaed115a8b8e93222e91412d3dcebd50720cc6..309005271391d28ff0c778a83e340324ef1bdb49 100644
--- a/src/parsing/preparser.h
+++ b/src/parsing/preparser.h
@@ -1009,8 +1009,8 @@ class PreParser : public ParserBase<PreParserTraits> {
   Statement ParseStatementListItem(bool* ok);
   void ParseStatementList(int end_token, bool* ok,
                           Scanner::BookmarkScope* bookmark = nullptr);
-  Statement ParseStatement(bool* ok);
-  Statement ParseSubStatement(bool* ok);
+  Statement ParseStatement(AllowLabelledFunctionStatement, bool* ok);
+  Statement ParseSubStatement(AllowLabelledFunctionStatement, bool* ok);
   Statement ParseScopedStatement(bool legacy, bool* ok);
   Statement ParseFunctionDeclaration(bool* ok);
   Statement ParseClassDeclaration(bool* ok);
@@ -1023,7 +1023,8 @@ class PreParser : public ParserBase<PreParserTraits> {
                                       Scanner::Location* first_initializer_loc,
                                       Scanner::Location* bindings_loc,
                                       bool* ok);
-  Statement ParseExpressionOrLabelledStatement(bool* ok);
+  Statement ParseExpressionOrLabelledStatement(AllowLabelledFunctionStatement,
+                                               bool* ok);
   Statement ParseIfStatement(bool* ok);
   Statement ParseContinueStatement(bool* ok);
   Statement ParseBreakStatement(bool* ok);