[civicrm.root] wrongly evaluated on Joomla

Under some circumstances, [civicrm.root] is evaluated as /components/com_civicrm/civicrm/ but should be /administrator/components/com_civicrm/civicrm/ resulting in various failures.

A workaround is to use the path instead of the variable.

For example, see https://civicrm.stackexchange.com/questions/27652/location-of-civicrm-css-on-joomla