[csswg-drafts] [selectors] Repeated "same as :first-child:last-child"

Loirooriol has just created a new issue for https://github.com/w3c/csswg-drafts:

== [selectors] Repeated "same as :first-child:last-child" ==
Commit be7492c added a sentence to [`:only-child`](https://drafts.csswg.org/selectors-4/#the-only-child-pseudo), but I think this was an unintended mistake, because the same sentence was already just below there.

> The :only-child pseudo-class represents an element that has no siblings, **same as :first-child:last-child. Same as :first-child:last-child** or :nth-child(1):nth-last-child(1), but with a lower specificity.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/1308 using your GitHub account