Lps 47663

This issue caused by user does not have a view permission for portlet 88 when user try to delete a page.

If a portlet is a system portlet that a use cannot manually add to their page (refer to  the comment of isSystem method of class PortletImpl) so since user can not add a system portlet to any page, so we should not check a  system portlet view permission on a specific page.