Fix a CSRF issue with adding new email addresses

Summary:
The first dialog was being given the wrong user (`$user`, should be `$viewer`), leading to a CSRF issue.

(The CSRF token it generated was invalid in all validation contexts, so this wasn't a security problem or a way to capture CSRF tokens for other users.)

Use `newDialog()` instead.

(This seems completely unrelated to the vaguely-similar-looking issues we saw earlier this week.)

Test Plan:
  - Added a new email address.
  - Clicked "Done" on the last step.
  - Completed workflow instead of getting a CSRF error.

Reviewers: chad, tide

Reviewed By: tide

Differential Revision: https://secure.phabricator.com/D16200

src/applications/settings/panel/PhabricatorEmailAddressesSettingsPanel.php

@@ -227,8 +227,7 @@ final class PhabricatorEmailAddressesSettingsPanel
 
           $object->sendVerificationEmail($user);
 
-          $dialog = id(new AphrontDialogView())
-            ->setUser($user)
+          $dialog = $this->newDialog()
             ->addHiddenInput('new',  'verify')
             ->setTitle(pht('Verification Email Sent'))
             ->appendChild(phutil_tag('p', array(), pht(
@@ -259,8 +258,7 @@ final class PhabricatorEmailAddressesSettingsPanel
           ->setCaption(PhabricatorUserEmail::describeAllowedAddresses())
           ->setError($e_email));
 
-    $dialog = id(new AphrontDialogView())
-      ->setUser($viewer)
+    $dialog = $this->newDialog()
       ->addHiddenInput('new', 'true')
       ->setTitle(pht('New Address'))
       ->appendChild($errors)