Added sketch for VM

DO NOT MERGE
This is just a sketch.
Please comment.
> I've added this since I am not sure whether we need to have a pointer to constructor the object struct.

The `new` operator returns a new object whose __proto__ has a non iterable but writable `constructor` property pointing to the constructor function. 

I don't think we should keep the constructor as part of each object's properties, nor part of the object struct.

https://gist.github.com/mmikulicic/7ed623a0f80b646e6db0