Add notification excerpts to help distinguish posts

js/forum/src/components/Notification.js

@@ -26,6 +26,9 @@ export default class Notification extends Component {
           {icon(this.icon(), {className: 'Notification-icon'})}
           <span className="Notification-content">{this.content()}</span>
           {humanTime(notification.time())}
+          <div className="Notification-excerpt">
+            {this.excerpt()}
+          </div>
         </a>
       </div>
     );
@@ -58,6 +61,15 @@ export default class Notification extends Component {
   content() {
   }
 
+  /**
+   * Get the excerpt of the notification.
+   *
+   * @return {VirtualElement}
+   * @abstract
+   */
+  excerpt() {
+  }
+
   /**
    * Mark the notification as read.
    */