Defined @namespace using CSS syntax (fixes #649)

[SebastianZ]

[css-namespaces-3] This replaces the CSS 2.1 syntax used to define the @namespace rule by the newer CSS Syntax 3 rules used in other specs.

[SebastianZ]

As I immediately got an error after creating the PR due to not having my GitHub account connected with my W3C account, I've done so now.

[svgeesus]

@fantasai do you think we should merge this? It is certainly better to use the more modern syntax. Namespaces 3 is a Rec so that would also mean issuing an erratum (which I can help with, if needed). Or indeed we could go through the steps to republish as an updated Recommendation.

I feel this is an editorial change and has no effect on actual implementations.

(I will deal with the IPR bot false positive, if we merge)

[tabatkins]

I think we should do it; the current definition isn't well-founded since CSS isn't defined over that grammar definition any longer.

[SebastianZ]

Sounds like this change could just be merged, but please let me know if I still have to change something.

Sebastian

[fantasai]

@svgeesus Given css-syntax-3 is a CR now, and it's effectively editorial, yeah, I think it's fine to merge. I'd want @tabatkins to review the changes though, since I'm not quite as familiar with the new syntax definition requirements. :)

Also, hopefully Process 2020 goes through and we should be able to publish an editorial update to the REC without too much hassle. ^_^

[tabatkins]

r+

[SebastianZ]

Thank you for merging this change, @tabatkins!

Sebastian