Temporary stop-gap fix for dynamic classes, so they pass the test.

Temporary stop-gap fix for dynamic classes, so they pass the test.

XXX This is not sufficient: if a dynamic class has no __repr__ method
(for instance), but later one is added, that doesn't add a tp_repr
slot, so repr() doesn't call the __repr__ method.  To make this work,
I'll have to add default implementations of several slots to 'object'.

XXX Also, dynamic types currently only inherit slots from their
dominant base.