fix: Use Object.getPrototypeOf to get prototype in __proto__-fn-name.js

[aapoalas]

As best as I can tell, this test is accidentally and very confusingly relying on the Annex B __proto__ getter when testing the spec-defined __proto__ key literal special case.

As an example: Node.js passes this test as it is currently, but Deno does not as Deno does not implement the __proto__ getters and setters.

[Ms2ger]

Please replace the es6id by the relevant esid

[aapoalas]

Please replace the es6id by the relevant esid

According to some documentation I found it's a deprecated: Should I update it or just remove it?

Also should I update the spec text quote?

[Ms2ger]

Replace by the key esid

[Ms2ger]

And yes, if the quoted spec text changed, please fix that too.

[aapoalas]

Replace by the key esid
And yes, if the quoted spec text changed, please fix that too.

Oops, sorry this slipped my mind somehow. I've now fixed the esid to point to PropertyDefinitionEvaluation as it should, and copied over the relevant steps from the spec text.

[Ms2ger]

Thanks!