Array.prototype.sort and toSorted with a comparator now run V8's
TimSort (array-sort.tq) step for step in the runtime, in the generated
sort for booleans and unions with undefined, and in the checked-value
sort. The comparator is called as f(x, y) < 0 in Node's argument order,
so a comparator sees Node's calls in Node's order and an inconsistent
comparator yields Node's permutation. Undefined values, including a
union's undefined arm, are set aside before sorting and never reach the
comparator, and a checked comparator's result converts with ToNumber.
Structured inputs take fewer comparator calls than the previous merge
sort. Each thread reuses one sort buffer of up to 1 MiB.
