[css-animations-1] No longer mark AnimationEvent.pseudoElement as at-risk

This closes #2647.

Author: birtles

css-animations-1/Overview.bs

@@ -34,7 +34,6 @@ Former Editor: Sylvain Galineau, Adobe, galineau@adobe.com
 
 Abstract: This CSS module describes a way for authors to animate the values of CSS properties over time, using keyframes. The behavior of these keyframe animations can be controlled by specifying their duration, number of repeats, and repeating behavior.
 
-At Risk: the <code>pseudoElement</code> property of the ''AnimationEvent'' interface
 Link Defaults: css-values-3 (type) <time>, cssom-1 (interface) cssstyledeclaration, dom-core-ls (interface) event, webidl (type) SyntaxError, css-position-3 (property) left
 Ignored Terms: domstring, float, animationeventinit, event, eventinit, eventtarget, document
 </pre>