[selectors-4][editorial] Removed At Risk: the column combinator as it is now in Selectors 5.

Author: svgeesus

selectors-4/Overview.bs

@@ -23,7 +23,6 @@ Former Editor: Peter Linss
 Former Editor: John Williams
 Abstract: <a>Selectors</a> are patterns that match against elements in a tree, and as such form one of several technologies that can be used to select nodes in a document. Selectors have been optimized for use with HTML and XML, and are designed to be usable in performance-critical code. They are a core component of <abbr title="Cascading Style Sheets">CSS</abbr> (Cascading Style Sheets), which uses Selectors to bind style properties to elements in the document.
 Abstract: Selectors Level 4 describes the selectors that already exist in [[!SELECT]], and further introduces new selectors for CSS and other languages that may need them.
-At Risk: the column combinator
 At Risk: [=user action pseudo-classes=] applying to non-[=tree-abiding pseudo-elements=]
 Ignored Terms: function token, Document, DocumentFragment, math, h1, shadow tree, querySelector(), quirks mode, button, a, span, object, p, div, q, area, link, label, input, html, em, li, ol, pre, CSS Value Definition Syntax
 Ignored Vars: identifier, i