f_extras+f_class bug on certain vehicles

[LudaPecurka]

f_extras child that has defined class and is located in bonnet_dummy will not spawn in-game. This only applies to cars that do not come with boot_dummy. Adding boot_dummy by hand will not change anything.

Meaning that if I wanted to have two types of bonnet on a car that doesn't have boot/trunk, I will not be able to do it as the bonnet will not spawn.

Tested on Elegy, Comet, Infernus and ZR350 (Infernus and ZR350 do not have a boot/trunk).