[mediaqueries][css-conditional] Allow empty functions in

[fantasai]

@andruud wrote in #6312 (comment)

The reason Chromium appears to evaluate not fn() to false in the demo is because not fn() is actually invalid grammar. (, requires one or more tokens).

Since this is about forwards-compatible parsing and evaluation, it seems to me it would make more sense if were optional so that empty functional notations would be syntactically valid.

[andruud]

Coincidentally, we actually made a ninja-edit for this last week. #6799

[tabatkins]

Yeah, the grammar was an accidental leftover from when was implicitly optional (but this caused more confusion than it solved). It was always intended that empty functions should be allowed, and the edits are in now to reflect that.

[fantasai]

Reopening to get WG approval on this, since it's updating a CR. Should be routine.

[css-meeting-bot]

The CSS Working Group just discussed Allow empty functions in , and agreed to the following:

• RESOLVED: Accept change to allow empty functional notations in

The full IRC log of that discussion

Topic: Allow empty functions in
github: https://github.com//issues/6803
TabAtkins: We had some leftover grammar from a previous change that accidentally implied that if you had a in functional form it had to ahve something inside the parens
TabAtkins: previously could be empty
TabAtkins: small change to make the value optional, so that foo() would be valid
@media fn() {...}
@media fn(foo) {...}
TabAtkins: wanted to make sure this counts as with unknown value rather than syntax error
florian: asking for approval because spec is in CR
RESOLVED: Accept change to allow empty functional notations in