__proto__: something should be rejected in the Record grammar

[rricard]

This was brought up in #71 (comment) but the following forms should be rejected by the parser:

#{
    __proto__: something,
    "__proto__": somehting,
}

[nicolo-ribaudo]

Note that

#{
  ["__proto__"]: something
}

would still be valid (because also in objects it sets a __proto__ property and not the prototype), this is just to avoid confusion since records don't have prototypes.

[rricard]

Yes! Thank you for the precision, I did discuss it in #71 (comment) but forgot to port it here