[css-mixins] `<combinator>` is already defined in Selectors

[cdoublev]

There is syntax and selector <combinator>s, which are different sets:

• https://drafts.csswg.org/selectors-4/#typedef-combinator
• https://drafts.csswg.org/css-mixins-1/#typedef-combinator

It would be nice to clarify whether/how productions should be able to expand to a different value definition (syntax) depending on context. As far as I know, <bool-test> is the only other production whose value definition is context-sensitive, but it does not explicitly expand to a value definition (with <bool-test> =).

[cdoublev]

I hope it is fine not top open a separate issue, but the same problem applies to <type()>:

• in CSS Mixins: type( <syntax> )
• in CSS Images 4: type( <string> )

If production rules should have context-insensitive value definitions, a solution could be to use an inline type() definition (like in CSS Images): <css-type> = <syntax-component> | type( <syntax> ).

Edit: never mind, type() is defined as a function in CSS Images, not as a type.

[tabatkins]

Yup, I went ahead and deduped the names.