Support for nested calc expressions in CSS values

[claudepache]

E.g.

.foo {
    width: calc(3em + calc(100px / 2)); /* equivalent to: calc(3em + (100px / 2)) */
}

This may be useful when working with CSS variables.
See https://developer.mozilla.org/en-US/docs/Web/CSS/calc#Nested_calc()_with_CSS_Variables for details.

Maybe the support for calc may be marked as "partial" if the browser does not support nested calc.

[jraoult]

@Fyrd would you consider a PR if I were to submit one for that? I just wasted a couple of hours on Safari for iOS not supporting it, so if I could avoid this pain to someone else it would make my day :)

[JaneX8]

+1

[brisourceful]

It would seem that IE 11 has many issues (3+ and counting) with supporting calc() as well. I think it would make more sense to mark this as 'partial' support. Then again, I don't know the qualifications for marking a browser as partial support. Would love to know what that is.

[GPHemsley]

Looks like this is now covered by MDN data:
https://caniuse.com/mdn-css_types_calc_nested

(via mdn/browser-compat-data#854)