Add tests of class for instances
Add tests of class for instances

The `FooClassIsBar` tests mostly fail because `Object.toString` is not
correct, behaving as it if called `.toString` on its `this` rather than
generating a string as described in the spec.

google/CodeCity,google/CodeCity,NeilFraser/CodeCity,NeilFraser/CodeCity,NeilFraser/CodeCity,google/CodeCity,google/CodeCity,NeilFraser/CodeCity