Fix regression with super() calls inside shared examples. Internal only.

- Current spec status:
  - 1.9.3-p484: 317 examples, 0 failures in 0.13683 seconds.
  - 2.0.0-p353: 331 examples, 0 failures in 0.14791 seconds.
  - 2.1.0:      331 examples, 0 failures in 0.10806 seconds.