Disallow generator declarations in certain locations

src/parsing/preparser.h

Index: src/parsing/preparser.h
diff --git a/src/parsing/preparser.h b/src/parsing/preparser.h
index 62581cf74d2b24d1ed3e656d5ef924d8317e3338..ecea789cc0f6f0aaf081dac108c7eb69672bee4d 100644
--- a/src/parsing/preparser.h
+++ b/src/parsing/preparser.h
@@ -1028,6 +1028,8 @@ class PreParser : public ParserBase<PreParserTraits> {
   Statement ParseSubStatement(AllowLabelledFunctionStatement allow_function,
                               bool* ok);
   Statement ParseScopedStatement(bool legacy, bool* ok);
+  Statement ParseHoistableDeclaration(bool* ok);
+  Statement ParseHoistableDeclaration(int pos, bool is_generator, bool* ok);
   Statement ParseFunctionDeclaration(bool* ok);
   Statement ParseClassDeclaration(bool* ok);
   Statement ParseBlock(bool* ok);