Otherwise, if complex expressions such as when expressions are
used in combination with the intrinsics we get incorrect stepping
behavior.
^KT-64341 Fixed
The patch adopts and reuses the optimizations from the legacy backend.
The optimizations remove useless temporary variables,
statements and simplify generated JS code.
The optimizations can be disabled by `-Xoptimize-generated-js=false`.
Related to KT-51139
We already have stepping tests for Kotlin/JVM.
They are helpful for testing the correctness of the generated
debugging information.
They are better than line number tests in that they allow to test the
_behavior_, not the generated data. The structure of the data may change
even if the behavior stays the same. For that reason, stepping tests
are more stable.