INVALID_FIELD_NAME_POSITIONAL reported even when there is no conflict

[scheglov]

The specification says: A field name that collides with the synthesized getter name of a positional field. For example: (int, $0: int) since the named field '$0' collides with the getter for the first positional field.

The example (int, $0: int) is weird and probably should be (int, {int $0}), but the intention seems to disallow only when there is a conflict, not always.

Happens for co19/LanguageFeatures/Records/record_type_annotations_A07_t02.

[bwilkerson]

The fix should wait until we have clarity on which names should be checked.

[scheglov]

co19/LanguageFeatures/Records/record_expressions_A05_t02

[scheglov]

co19/LanguageFeatures/Records/record_type_annotations_A05_t05

[bwilkerson]

I believe that this should now be fixed by https://dart-review.googlesource.com/c/sdk/+/260682