Bug 1406964 - Fading out the toolbar buttons should use a quicker easing function. r=Gijs

MozReview-Commit-ID: Esopfx645qF

--HG--
extra : rebase_source : cfca0d386cf76ee93bd6cc09b21e6f79a735bdf7

browser/themes/shared/customizableui/panelUI.inc.css

@@ -473,6 +473,7 @@ photonpanelmultiview .panel-subview-body {
   animation-name: widget-animate-out;
   animation-fill-mode: forwards;
   animation-duration: 500ms;
+  animation-timing-function: var(--animation-easing-function);
 }
 
 @keyframes widget-animate-out {