last-exclusive progressions (i.e., "until" progressions and loop over
array indices).
This change makes it possible to correctly implement the handling of
"step" progressions. Computing the last element of a stepped progression
requires that the last is inclusive.
Also invert the while loop (into if + do-while) that is used when
lowering for-loops over progressions that cannot overflow. This keeps
the performance characteristics closer to the ForLoopsLowering in
kotlin-native, since the goal is to converge to this shared version.
Also used IrType instead of KotlinType, where possible.
https://github.com/JetBrains/kotlin/pull/2390https://github.com/JetBrains/kotlin/pull/2305
