[css-typed-om] Should min and max methods on CSSNumericValue preserve percentage values?

CSSNumericValues have a min and a max method.

If min or max is called and all of the values are CSSUnitValues with the same unit, the steps of the method will return early with a CSSUnitValue with the minimum or maximum value respectively.

If all of the items in values are CSSUnitValues and have the same unit, return a new CSSUnitValue whose unit internal slot is set to this’s unit internal slot, and value internal slot is set to the minimum of the value internal slots of the items in values.

But, if the unit is percent we can't really know what value it will resolve against at this point. Since percentages might resolve against a negative basis, returning a CSSUnitValue with the minimum or maximum of the values could end up with the opposite result of what is expected (see simplify a calculation tree).

Should this step in the methods be skipped if the unit is percent?

Start with the CSS Typed OM definitions of CSSNumericValue min() and max(), then read the CSS Values 4 section on simplifying calculation trees. Determine whether the early-return rule is valid for percent units with potentially negative bases. Done means the Working Group resolves the question and the affected specification algorithm is updated accordingly.