According to wasm's spec, nearest must do the following, for NaN inputs:
- when the input is a canonical NaN, return a canonical NaN;
- when the input is a non-canonical NaN, return an arithmetic NaN.
This patch adds checks when the exponent is all ones if the input was a
NaN, and will set the significand's most significant bit in that case.
It works both for canonical inputs (which already had the bit set) and
makes other NaN inputs canonical.
04cf94cea3