Don't pass self in the environment slot.

[luqmana]

I think the intention was to have this not be the case.

[brson]

cc #6974

[metajack]

Visiting for triage. I think this bug could use a little more description. I don't have much idea what the problem is, or why UFCS is related.

[thestinger]

Nominating for the production ready milestone. This is a source of undefined behaviour in our IR.

[catamorphism]

accepted production-ready