TBESEN.ObjectInstanceOf does not support classes registered with RegisterNativeObject

[JernejL]

class registered in pascal:

BesenInstance.RegisterNativeObject('Vehicle', TVehicleInterface);

in javascript:

`var tvehicle = new Vehicle(VehicleIdent, SpawnX, SpawnY, SpawnZ, Heading, immediate_create);

if (tvehicle instanceof Vehicle) alert('yes');`

new Vehicle works properly as expected, creates a instance of the object.

instanceof however fails, and triggers exception "Prototype not object" in TBESENObjectFunction.HasInstance.