Revert "Data.Closure: from_operator() with dots fails for some reason. Log it as a spec case."

This reverts commit a30a5740a7437b05a10eb12baf7dc1597ffec033.
Revert "Data.Closure: initial spec: spec for from_operator"

This reverts commit 8fdfdb44453a69492ede9d366af955ed1b98b08a.