Toolbar: A11y: Fix color contrast for zero comments.

Remove the 50% opacity change for when the adminbar comment indicators has zero comments.

Props louischan, hbhalodia, sabernhardt, joedolson.
Fixes #64811.

git-svn-id: https://develop.svn.wordpress.org/trunk@61861 602fd350-edb4-49c9-b593-d223f7449a82

Author: joedolson

src/wp-includes/css/admin-bar.css

@@ -596,10 +596,6 @@ html:lang(he-il) .rtl #wpadminbar * {
 	top: 3px;
 }
 
-#wpadminbar #wp-admin-bar-comments .count-0 {
-	opacity: .5;
-}
-
 /**
  * New Content
  */