[css-values-5] *-interpolate() with equal stop positions or without segments #14313

https://drafts.csswg.org/css-values-5/#interpolation-notation

What should be the result of these functions?

1. calc-interpolate(1, 0: 0, 1: 1, 1: 2)
2. calc-interpolate(1px, 0px: 1)
3. calc-interpolate(1, 0: 0)

For (1), it depends on which of { x: 1, y: 1 } or { x: 1, y: 2 } takes precedence. I would say that if any stop has an input position that is equal to one or more preceding stops, it replaces them. Thus, calc-interpolate(0.5, 0: 0px, 1: 1px, 1: 1em) would serialize with calc-interpolate(0.5, 0: 0px, 1: 1em) as a component of a declared value.

For (2), if I am not mistaken, it defines an interpolation map from and to 0px. I would say that if there is a single stop and the interpolation progress is lower or greater than its input position, the resolved value is -infinity or +infinity, respectively.

For (3), it does not appear to define any segment. I would say the same applies as for (2).