Comment by systoll

Two changes lead to three failures in Chrome.

The first change is described in the 'note' at https://drafts.csswg.org/selectors-4/#child-index

Chrome is failing a test because the root node claims to be a 'first-child'.

The root node is the first sibling, but since it doesn't have a parent, the selectors 3 spec didn't include it.

The selectors 4 draft does away with the requirement that a 'first-child' have a parent, and chrome's behaviour matches.

The second is discussed here https://github.com/whatwg/dom/issues/319

Roughly, when interpreting qualified names, Chrome is throwing InvalidCharacterErrors when the acid test wants it to throw NamespaceErrors, in situations where you really have both. This leads to two tests failing.