Display Dashboard icon instead of the home icon in toolbar when the link leads to Dashboard.

props ghost1227.
fixes #26754.

git-svn-id: https://develop.svn.wordpress.org/trunk@28599 602fd350-edb4-49c9-b593-d223f7449a82

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

@@ -509,6 +509,10 @@ html:lang(he-il) .rtl #wpadminbar *  {
 }
 
 #wpadminbar #wp-admin-bar-site-name > .ab-item:before {
+	content: "\f226";
+}
+
+.wp-admin #wpadminbar #wp-admin-bar-site-name > .ab-item:before {
 	content: "\f102";
 }