Before:
```
[2020-12-17 11:33:46] (211s) Tuple counts for ControlFlowGraphImpl::Trees::RescueEnsureBlockTree::nestedEnsure_dispred#ff/2@2ea588:
11409019 ~0% {2} r1 = SCAN ControlFlowGraphImpl::getScope#ff AS I OUTPUT I.<1>, I.<0> 'this'
3714296409 ~0% {3} r2 = JOIN r1 WITH ControlFlowGraphImpl::Trees::getAChildInScope#fff_102#join_rhs AS R ON FIRST 1 OUTPUT r1.<1> 'this', R.<1>, R.<2>
2359 ~0% {2} r3 = JOIN r2 WITH ControlFlowGraphImpl::Trees::RescueEnsureBlockTree::getAnEnsureDescendant#ff AS R ON FIRST 2 OUTPUT r2.<2>, r2.<0> 'this'
1 ~0% {2} r4 = JOIN r3 WITH ControlFlowGraphImpl::Trees::RescueEnsureBlockTree::getEnsure_dispred#ff_10#join_rhs AS R ON FIRST 1 OUTPUT r3.<1> 'this', R.<1> 'innerBlock'
return r4
```
After:
```
[2020-12-17 15:20:37] (51s) Tuple counts for ControlFlowGraphImpl::Trees::RescueEnsureBlockTree::nestedEnsure_dispred#ff/2@c4f57d:
635 ~1% {3} r1 = JOIN ControlFlowGraphImpl::Trees::RescueEnsureBlockTree::getEnsure_dispred#ff_10#join_rhs AS L WITH ControlFlowGraphImpl::Trees::getAChildInScope#fff_201#join_rhs AS R ON FIRST 1 OUTPUT R.<1>, L.<1> 'innerBlock', R.<2>
1 ~0% {3} r2 = JOIN r1 WITH ControlFlowGraphImpl::Trees::RescueEnsureBlockTree::getAnEnsureDescendant#ff_10#join_rhs AS R ON FIRST 1 OUTPUT R.<1> 'this', r1.<2>, r1.<1> 'innerBlock'
1 ~0% {2} r3 = JOIN r2 WITH ControlFlowGraphImpl::getScope#ff AS R ON FIRST 2 OUTPUT r2.<0> 'this', r2.<2> 'innerBlock'
return r3
```
Lambda bodies are parsed as nested do-blocks or normal blocks.
This is actually incorrect, as the body of a lambda can't have
parameters. However, we can "inline" such blocks to get the
desired control flow.
