[Records] Annotation space record type annotation parsing

[scheglov]

@jensjoha

The language specification decided on dart-lang/language#2469
So, the parser should be updated accordingly.

[leafpetersen]

I believe, per discussion with @johnniwinther that this change was proposed to land after the cut for 2.19 at the end of the month to avoid the breaking change landing in 2.19. (We agreed that the already landed breaking change around try/catch would remain and go out in 2.19).

[jensjoha]

Fixed with 6bce0d6.