[css-align] should be clearer about whether 'align-content' applies to single-line flex containers

[dbaron]

In flexbox, it was clear that align-content only applies to multiline flex containers.

But the alignment spec says:

For align-content, the flex lines.

This wording makes it sound like it might do something for single-line flex containers. I tend to think it should be clearer that it doesn't. But if, instead, the intent is that it does, I think it should be much more explicit. (And I'd be a little worried about compatibility.)

[fantasai]

Fixed in e1ddeea, thanks!

[fantasai]

(I think it's a bit unfortunate that it doesn't apply to single-line flex containers, but this at least makes the specs more clearly consistent.)