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
- Don't produce mapping for closing bracket in case of expressionBody
- Map Kt*Function declaration into corresponding js fun declaration
- Update test data & add new test
Before this change we set JsSwitch source to subject's JsExpression.
We ignore these types of source elements during:
1. js ast serialization (see 'JsAstSerializer.extractLocation');
2. source map generation (see 'SourceMapBuilderConsumer.addMapping').
However we might add indent during source generation
(see 'JsToStringGenerationVisitor.pushSourceInfo').
That seemingly broken 'testEnumEntryRemoved' in
'IncrementalJsCompilerRunnerTestGenerated.ClassHierarchyAffected',
because deserialized ast during incremental build would not
have source element at all (JsExpression was ignored), but ast
during rebuild would have JsExpression source element.
Alexander Korepanov