Let iRevertIntros ensure that we are in the proofmode.

This fixes issue #61.
2 jobs for master in 10 minutes and 29 seconds (queued for 16 minutes and 20 seconds)
Status Job ID Name Coverage
  Test
passed #2248
coq
iris-coq8.5.3

00:05:49

passed #2249
coq
iris-coq8.6

00:04:40