Upon changing to a new comment thread, fixes the the bug of the RHS scrolling to whitespace below the pane

web/react/components/post_right.jsx

@@ -294,6 +294,8 @@ module.exports = React.createClass({
         });
     },
     componentDidUpdate: function() {
+        $(".post-right__scroll").scrollTop($(".post-right__scroll")[0].scrollHeight);
+        $(".post-right__scroll").perfectScrollbar('update');
         this.resize();
     },
     componentWillUnmount: function() {