REFACTOR: Remove _.uniq and use ember version

app/assets/javascripts/discourse/app/lib/link-mentions.js

@@ -70,9 +70,9 @@ export function linkSeenMentions($elem, siteSettings) {
         .substr(1)
     );
     updateFound($mentions, usernames);
-    return _.uniq(usernames).filter(
-      u => !checked[u] && u.length >= siteSettings.min_username_length
-    );
+    return usernames
+      .uniq()
+      .filter(u => !checked[u] && u.length >= siteSettings.min_username_length);
   }
   return [];
 }

app/assets/javascripts/discourse/app/models/user.js

@@ -864,7 +864,8 @@ const User = RestModel.extend({
       }
     });
 
-    return _.uniq(titles)
+    return titles
+      .uniq()
       .sort()
       .map(title => {
         return {