[css-color-hdr] How should checking for percentages summing to 0 work in dynamic-range-limit-mix() and color-mix() when calc() is used? #11678
Description
The text for dynamic-range-color-mix() contains this statement:
If the sum of all percentages is 0%, then the function is invalid.
If the intent is that this is checked at parse time, which is when things are usually marked invalid, what should happen for calc() values that aren't resolvable until style building?