[immutable-arraybuffer] ArrayBuffer.prototype.transferToImmutable

[gibson042]

Ref #4509

New ArrayBuffer.prototype properties

• ArrayBuffer.prototype.transferToImmutable
  • verifyPrimordialCallableProperty(ArrayBuffer.prototype, "transferToImmutable", "transferToImmutable", 0);
  • brand-checking (throws TypeError unless receiver is an ArrayBuffer and not a SharedArrayBuffer), before coercing newLength
  • defaults newLength to [[ArrayBufferByteLength]]
  • if newLength is not undefined, casts it to an index (integral number from 0 to 2**53 - 1 inclusive) or throws a RangeError for out-of-range values, after brand-checking
  • throws TypeError if receiver is detached or immutable, after processing newLength (note the unusual receiver-after-argument order)
  • detaches the receiver
  • returns an immutable ArrayBuffer with the correct length
  • if newLength ≤ [[ArrayBufferByteLength]], returns an ArrayBuffer with contents matching the appropriate prefix of the receiver up to exclusive index newLength
  • if newLength > [[ArrayBufferByteLength]], returns an ArrayBuffer with contents matching those of the receiver, followed by the appropriate count of zeros

[Ms2ger]

I don't think this belongs here

[Ms2ger]

I'm willing to accept this test, but I think it would be nicer if we could have a generic helper function that runs through a set of interesting ToIndex arguments; this isn't the only API that could be tested in this way.

[Ms2ger]

This doesn't take into account that sourceMakers[i] might be undefined.

[Ms2ger]

Calculating the argument based on the index in the array seems a recipe for confusion

[Ms2ger]

Same here

[Ms2ger]

This is very convoluted, probably too much so