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
Namely:
- Generate debug info for closing braces, which allows the breakpoints
set on closing braces to be hit
- Generate debug info for 'if' and 'try/catch' statements.
KT-46276
Reimplement the same hacky approach used in the old backend (see
cc2fe6b0c6).
Previously, the debugger incorrectly stepped into Collections.kt on
"step over" inline function calls from stdlib like 'any'.
Since `if` and `when` expressions are represented the same way in IR,
the behavior is fixed for both of them. It's not the case in the old JVM
backend, where stepping over `when` conditions still suffers from the
same problem, which the newly added test checks.
Artem Kobzar