fix: invalid assert removed (CURA-2296)
fix: invalid assert removed (CURA-2296)

assertion didn't hold for lines with a very shallow angle

Ultimaker/CuraEngine,ROBO3D/CuraEngine,ROBO3D/CuraEngine,alephobjects/CuraEngine,Ultimaker/CuraEngine,alephobjects/CuraEngine,ROBO3D/CuraEngine,alephobjects/CuraEngine