note that std::numeric_limits<uint64_t>::max() and
std::numeric_limits<int64_t>::max() aren't exactly representable in a
double, so we need to be strictly less to be definitely lossless

UBSAN gave during Value.IsLosslessDouble test:
include/rapidjson/document.h:955:42: runtime error: value 1.84467e+19 is outside the range of representable values of type 'unsigned long'