Update calc() with color value support

[chrisdavidmills]

No description provided.

[teoli2003]

LGTM, r+

[foolip]

@teoli2003 do you think there's a way to figure out, years later, what change in Firefox 59 this entry was about? I asked colleagues if Chrome supports this, and it's not clear what the feature actually is, how to test it.

[foolip]

I'll also loop in @Elchi3 to ask, since he updated this data for Safari in #4567, saying "css.types.calc.color_values worked for me in Safari 8 in Saucelabs". Florian, do you know what this feature is and how to test it?

[Elchi3]

Florian, do you know what this feature is and how to test it?

I think this is color: rgb( calc(255 - 0) ,0,0); implemented in https://bugzilla.mozilla.org/show_bug.cgi?id=984021. Maybe this shouldn't be a subfeature but rather partial support if a browser isn't able to do it?

[foolip]

I see, so this is actually about calc() inside color functions, not about doing calc() with colors. Should this feature be moved to somewhere else then?

[Elchi3]

Either move it, use partial support, or omit entirely if it doesn't seem all that relevant. BCD can't capture every detail imo.

[foolip]

I've turned it into a note in #13486.