1823446 - Simplify NaN min/max expressions correctly

Status: NEW

(Core :: CSS Parsing and Computation, defect)

Description

[Oliver Medhurst [:canadahonk]]

New WPT tests (not landed upstream yet) added in patch for Bug 1820412 show that we also don't simplify min()/max() expressions with NaN arguments correctly. Split up from that bug for ease of patching.

Incompatible mixed units should not be simplified, even with NaN. Expected examples:
calc(1 * min(NaN * 1pt, NaN * 1cm)) -> calc(NaN * 1px) - compatible mixed, simplify
calc(1 * min(NaN * 2px, NaN * 4em)) -> min(NaN * 1px, NaN * 1em) - incompatible mixed, no simplification
calc(1 * clamp(NaN * 2em, NaN * 4px, NaN * 8pt)) -> clamp(NaN * 1em, NaN * 1px, NaN * 1px) - some compatible, but one incompatible, so no simplification (note unit pt goes to canonical px still though)