Body.enable only exists in Arcade physics, so move conditions concerning...

https://github.com/photonstorm/phaser/commit/9c35dfde0c8588789dd5430238d263c64dc4dea2 introcuded Arcade.Body.enable

The other physic engines don't have this property, so their post and preUpdate will not be executed.

This pull request fixes this.

Greetings, 
-- Phaiax