A `SwitchBreak` node should not have a specific associated
`FallThroughScopeType`, since its semantics represent the fact of a
`case` of the `switch` with no associated statements, and thus can be
represented with the `FallThrough` behavior.
We introduce the PromoteCallNoReturn beautification pass. Its goal is to
restructure sequence of statements, in order to have `call`s to
`noreturn` functions as _inlined_ in the middle of the statement
sequence, and leave _non local control flow statements_ at the end of
that scope. E.g., we prefer:
```
if (cond)
call noreturnfunc();
return;
```
to
```
if (!cond)
return;
call noreturnfunc();
```
In order to do this, contextually, we restructure the routine computing
the `fallthrough` property, in order to be able to differentiate between
the _non local control flow statements_, a call to a `noreturn`
function, or a generic mix of the two (useful when combining results
from the two situations above).
The new analysis is also used in the `promoteNoFallThrough` promotion
pass.
Alessandro Di Federico