Add type=submit to AphrontDialogView

Summary: This is required for browsers <= IE7

Test Plan: Inspected HTML for type.

Reviewers: epriestley

Subscribers: aran, epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D8503

src/view/AphrontDialogView.php

@@ -131,6 +131,7 @@ final class AphrontDialogView extends AphrontView {
         array(
           'name' => '__submit__',
           'sigil' => '__default__',
+          'type' => 'submit',
         ),
         $this->submitButton);
     }