Tests using __proto__ without appropriate features entry

[linusg]

Found some randomly (there may be more, only did a quick search):

test262/test/built-ins/TypedArrayConstructors/ctors/no-species.js

Line 29 in e4f91b6

assert.sameValue(mysteryTA.buffer.__proto__, ArrayBuffer.prototype);

test262/test/staging/ArrayBuffer/resizable/oobbehaves-like-detached.js

Line 25 in e4f91b6

i8a.__proto__ = { 2: 'wrong value' };

test262/test/staging/ArrayBuffer/resizable/typed-array-prototype.js

Line 52 in e4f91b6

assert.sameValue(ta_ab.__proto__, ta_rab.__proto__);

Unless __proto__ is actually relevant to the test, Object.get/setPrototypeOf() should be preferred IMO. __proto__ is "Normative Optional, Legacy", so new engines may not want to implement it (which is how I ended up here to begin with :^)).

For reference:

test262/features.txt

Line 258 in e4f91b6

__proto__

[ljharb]

Instead of using Object.getPrototypeOf, there should probably be a test helper that uses both, since there are engines that have dunder proto but not getPrototypeOf.