Fix $classes not imploding properly in list view

Summary: Fixes the persistent chat hyperlinks showing.

Test Plan: Open persistent chat, no longer see the hyperlinks showing. Close and open chat. Edit room.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D17216

src/view/phui/PHUIListItemView.php

@@ -249,7 +249,7 @@ final class PHUIListItemView extends AphrontTagView {
         $name = phutil_tag(
           'span',
           array(
-            'class' => $classes,
+            'class' => implode(' ', $classes),
           ),
           array(
             $this->name,