Use self._definition instead of local definition parameter
Use self._definition instead of local definition parameter

This is supposedly more defensive coding.

Contributes to issues CURA-1278 and CURA-351.

ynotstartups/Wanhao,Curahelper/Cura,hmflash/Cura,Curahelper/Cura,fieldOfView/Cura,fieldOfView/Cura,totalretribution/Cura,senttech/Cura,ynotstartups/Wanhao,senttech/Cura,totalretribution/Cura,hmflash/Cura