[N-API] `napi_get_value_string_length` return length as type too small

[dead-claudia]

As specified in the N-API documentation, napi_get_value_string_length returns the string length as an int, but the JS spec mandates it to be an unsigned integer at most 2⁵³-1. It may be more appropriate here to return a uint64_t instead.

(BTW, I use "return" loosely, in reference to its out parameter.)

[addaleax]

That should probably be removed from the API documentation, it’s no longer part of what Node exports. Also, you’re right, and we do use size_t now, which is the appropriate type for this kind of value.

[jasongin]

Yes, that API was removed because it was ambiguous about the encoding used to determine the length, and it was redundant with napi_get_value_string_utf8/16. The doc is out of date.

See also #13469 about other areas the doc needs updating.

[mhdawson]

I'll take a look at updating the docs tomorrow.