[css-values-4] Calc serialization links to a publicly-inaccessible discussion

[AtkinsSJ]

At the top of the Mathematical Expressions/Serialization section, we have this note:

ISSUE 3
This section is still under discussion.

(And likewise this is in the published W3C version.)

There are a few issues with this, as an implementer:

• What aspects are undecided?
• Is it even still under discussion? Judging by the URL that discussion is from almost 9 years ago.
• If there are still parts of this that need ironing out, excluding non-csswg implementers (unintentionally or not) means fewer people are able to collaborate the remaining problems.

It's true that css-values-4 is in working draft status, but in practice, calc() has long been in common use and websites (and WPT) rely on specific serialization behaviour.

[cdoublev]

I see this note above the procedure to serialize a mathematical function:

This section is still under discussion.

But access to the link target is restricted to W3C members.

Ugh, yeah it is; someone made a mistake and sent technical feedback to the private list in reply to a telcon agenda announcement. Don't worry, it's not relevant anymore and I should just remove it. (The behavior under discussion was resolved years ago and is widely implemented.)

#6506 (comment)

[AtkinsSJ]

Ah OK, so it's just accidental that it's still here 3 years later. 😅

I came across some other issues with calc serialization, so I'll put together a PR for them, and include that.