[css-easing-2][editorial] Add Tab and Chris as editors

Author: svgeesus

css-easing-2/Overview.bs

@@ -9,6 +9,8 @@ ED: https://drafts.csswg.org/css-easing/
 TR: https://www.w3.org/TR/css-easing-2/
 Editor: Brian Birtles, Mozilla https://www.mozilla.org/, bbirtles@mozilla.com, w3cid 43194
 Editor: Dean Jackson, Apple Inc https://www.apple.com/, dino@apple.com, w3cid 42080
+Editor: Tab Atkins Jr., Google, http://xanthir.com/contact, w3cid 42199
+Editor: Chris Lilley, W3C, https://svgees.us/, w3cid 1438
 Former Editor: Matt Rakow, Microsoft, w3cid 62267
 Former Editor: Shane Stephens, Google, shans@google.com, w3cid 47691
 Former Editor: Jake Archibald, Google, jakearchibald@google.com, w3cid 76394