Allow for null parameters in fn types for stringify
Allow for null parameters in fn types for stringify

dtao/doctrine,googlearchive/doctrine,demands/doctrine,fivetran/doctrine,petebacondarwin/doctrine,jifeon/doctrine,mysticatea/doctrine,Constellation/doctrine,jifeon/doctrine,Constellation/doctrine,jonathanKingston/doctrine,mysticatea/doctrine,PolymerLabs/doctrine,aeisenberg/doctrine,ecomfe/doctrine2,ecomfe/doctrine2,PolymerLabs/doctrine,googlearchive/doctrine