fix: remove notification from state before calling onRemove

Author: szdc

src/NotificationSystem.jsx

@@ -70,13 +70,13 @@ var NotificationSystem = React.createClass({
       return toCheck.uid !== uid;
     });
 
-    if (notification && notification.onRemove) {
-      notification.onRemove(notification);
-    }
-
     if (this._isMounted) {
       this.setState({ notifications: notifications });
     }
+
+    if (notification && notification.onRemove) {
+      notification.onRemove(notification);
+    }
   },
 
   getInitialState: function() {