Accessibility: Improve color contrast updating any #999 gray used for text or icons to a darker gray.

Fixes #35660.
Built from https://develop.svn.wordpress.org/trunk@36587


git-svn-id: http://core.svn.wordpress.org/trunk@36554 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/css/install-rtl.css

@@ -97,7 +97,7 @@ label {
 	background-size: 84px;
 	background-position: center top;
 	background-repeat: no-repeat;
-	color: #999;
+	color: #444; /* same as login.css */
 	height: 84px;
 	font-size: 20px;
 	font-weight: normal;