unittest: add expected results `(:return :normally)`
unittest: add expected results `(:return :normally)`

The form is expected to return normally without error. Return values
can be anything.
It causes failure of `(:results :unexpected-error ..)` when the form
signalled an error.

NobuoK/xyzzy,NobuoK/xyzzy,NobuoK/xyzzy,NobuoK/xyzzy,NobuoK/xyzzy