[css-color][css-values] Merge <alpha-value> and <cmyk-component> in <color-component>

[Crissov]

As already mentioned in #4477, <alpha-value> is redundant with <cmyk-component>, because both are effectively defined as <number [0.0, 1.0]> | <percentage>. Since color() shall allow either type as well #3450, it would make sense to have a single value type <color-component> for all of these, even if we can never have a generic <number-percentage> type in css-value.

[svgeesus]

is redundant with ,

Sure, if all you care about is syntactic level and nothing about documentation, understandability or semantics.

Closing this as pointless.

[Crissov]

I care about ease of understanding of specifications. The semantics are also the same, really.

[Crissov]

Also, apparently <alphavalue> is going to be killed in #3139.