Maps and sets incorrectly distinguish NaN values

[gibson042]

Environment: XS 11.6.0 32 4

Description XS incorrectly differentiates NaN values in maps and sets.

Steps to Reproduce

(new Set([NaN, Number("x"), Math.sqrt(-1), Infinity * 0, Infinity - Infinity])).size // => 2
(new Map([[NaN, true]])).get(Infinity / Infinity) // => undefined

Expected behavior
All NaN values should be indistinguishable from each other, with the first expression above returning 1 and the second returning true because both Map Objects and Set Objects specify that "distinct [key] values are discriminated using the SameValueZero comparison algorithm", which via Number::sameValueZero must return true when both operands are NaN.

Actual behavior
XS maps and sets differentiate NaN from constructed NaN values.

[phoddie]

Thank you!

XS normalizes zero for Map and Set keys here:

moddable/xs/sources/xsMapSet.c

Lines 916 to 920 in 40cf4e4

	else if (XS_NUMBER_KIND == kind) {
	if (slot->value.number == 0)
	slot->value.number = 0;
	sum = *((txU8*)&slot->value.number);
	}

Extending that to also normalize NaN gives the expected result:

		else if (XS_NUMBER_KIND == kind) {
			if (slot->value.number == 0)
				slot->value.number = 0;
			else if (c_isnan(slot->value.number))
				slot->value.number = C_NAN;
			sum = *((txU8*)&slot->value.number);
		}

Some more careful review and test262 testing will be needed to be sure this is a correct fix.