Handle infinities, NaN, and signed zero values #2705
Description
Math functions can produce these numbers, and we have to:
- keep them during calculation steps,
- check ranges for computed and used values.
The first step is probably limited to math functions, and should be quite easy to fix as Python floats are IEEE-754.
The second stem is both more important and complex to fix, as the computed-to-used-values conversion is often implicit and split all over layout and drawing steps, easily leading to crashes and invalid PDF generation.