No method provided to upload images in CiviMail

When sending email the Image Properties dialog is displayed as expected, but there is no Browse Server button. Also missing is the Upload tab.

To recreate:
Go to http://d46.demo.civicrm.org/
Click Mailings | New Mailing
Click image icon in HTML CKeditor.

When sending an email from a contact's profile screen the above problems are not observed.

Re: http://forum.civicrm.org/index.php/topic,36267.0.html.