Confusion between named and positional fields in a records test

[chloestefantsova]

It seems that the named and the positional fields are confused in some lines in https://github.com/dart-lang/co19/blob/master/LanguageFeatures/Records/type_promotion_A01_t02.dart.

1. In line 32 it should say ({int? n, String o}) instead of (int? n, String o).
2. In line 44 it should say (s: "Lily was here",) instead of ("Lily was here",).