Variables which type is determined thanks to instanceof checks should be usable as arguments without casts

The current implementation of the type checker allows to use methods of an object without the need of an explicit cast if it is wrapped in a proper instanceof check:

class A {
   void foo() {}
}
def o
...
if (o instanceof A) {
   o.foo()
}

But it doesn't work if the object is used as an argument:

class A {}
void m(A a) { ... }
def o
...
if (o instanceof A) {
   m(o) // requires m((A) o) which should not be necessary
}