Fix test crashes in KWRealObjectStubTest

It *appears* as if it's no longer necessary to call `[super dealloc]` in
`KWInterceptedDealloc()`. After removing this call, the tests seem to
run just fine with no crashes.

Note: I really have no idea if this is the correct fix! But it seems to work in any case? ¯\_(ツ)_/¯