It now passes all of the tests in 15.1.2.2-1 (except that parseInt
still has the .length property, which is a different bug) - so I'll
close the bug.
Still possibly at issue is whether we conform to ECMA language about
decimal numbers that are too large to fit in a double. I treat
decimal digits after the 20th as zero, but there could be some
floating-point rounding wackiness going on. In particular - are we
doing the right thing for numbers that are powers of 2, but larger
than 2^54, that are representable in a double?