Fixed fromDocument usage in .cms-tree
Fixed fromDocument usage in .cms-tree

See https://github.com/silverstripe/silverstripe-cms/pull/823

silverstripe/silverstripe-cms,dhensby/silverstripe-reports,dhensby/silverstripe-cms,silverstripe/silverstripe-siteconfig,silverstripe-labs/silverstripe-reports,jonom/silverstripe-cms,dhensby/silverstripe-cms,dhensby/silverstripe-reports,jonom/silverstripe-cms,helpfulrobot/i-lateral-silverstripe-siteconfig,silverstripe-labs/silverstripe-reports,silverstripe/silverstripe-cms,dhensby/silverstripe-cms