Add deleted in r732 (don't know why) functionality that displays custom Error page when linkname in Developer User Profile url doesn't exist (/site/user/profile/<not_existing_linkname>).
Patch by: Pawel Solyga
Review by: to-be-reviewed
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>blank_page</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<script type="text/javascript">
parent.TemplateDialog.loadCSSFiles(document);
</script>
</head>
<body id="mceTemplatePreview" class="mceContentBody">
</body>
</html>