Use EditEngine stacked comments in Diffusion

Summary: Ref T10978. Ref T8739. Fixes T10446. Converts Diffusion to modern comment/preview code, like Differential.

Test Plan: {F2342933}

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10978, T10446, T8739

Differential Revision: https://secure.phabricator.com/D17183

src/applications/differential/controller/DifferentialRevisionViewController.php

@@ -463,12 +463,7 @@ final class DifferentialRevisionViewController extends DifferentialController {
     }
 
     Javelin::initBehavior('differential-user-select');
-
-    Javelin::initBehavior(
-      'differential-keyboard-navigation',
-      array(
-        'haunt' => null,
-      ));
+    Javelin::initBehavior('differential-keyboard-navigation');
 
     $view = id(new PHUITwoColumnView())
       ->setHeader($header)