Helper function to declare and initialize the vtable.

The main "translation" pass for methods. Generates code for non-monomorphized methods only. Other methods will be generated once they are invoked with specific type parameters, see trans::base::lval_static_fn() or trans::base::monomorphic_fn().

Same as trans_trait_callee() above, except that it is given a by-ref pointer to the object pair.

Generates the code to convert from a pointer (Box<T>, &T, etc) into an object (Box<Trait>, &Trait, etc). This means creating a pair where the first word is the vtable and the second word is the pointer.