[selectors-api] some doubts

Howdy.

I have the following doubts about the selectors api spec.

1) How do we deal with node.querySelectorAll(">foo") ?
  should this be considered a valid selector and return children of the  
context node with nodeName equal foo ?
  This is a valid use case, and widely used and supported by existing  
libraries.

2) How should following pseudo-classes be handled?
  :hover -> make this use case clear. Should hovered element be matched, or  
the class ignored ?
  :root -> should node.querySelectorAll(":root ...") jump to the document  
root and use the entire document as context ?

3) How should pseudo-elements be handled ?
  ::first-line
  ::first-letter
  ::selection
  ::before
  ::after pseudo-elements
  none of these elements are visible to the DOM, and ::selection contains a  
too complex data structure which cannot be represented with a NodeList.

Thanks.