Knocking off two more vestiges of legacy switch

[Brian Goetz]

> It is common for math library methods to have a preamble to screen out 
> special values (infinities, NaN, 0.0, 1.0, etc.).
>
> This would be a reasonable use of a switch on float/double switch.
>
>

Which raises some questions (again) of the semantics of constant 
patterns for exotic floating point values, especially (again) negative zero.