~~~ move patternMatching tests to expression/when
~~~ move and rename ifInsideWhen test to when folder
~~~ rename and move misc/cases/defaultArguments.kt test to defaultArguments/cases/complexExpressonAsDefaultArgument.kt
~~~ add mergeStatementInBlockIfNeeded to JsAstUtils
~~~ do not use block for default argument if not needed
JS backend: fix dangling else issue in generated code for JsToStringGenerationVisitor
~~~ refactor WhenTranslator, remove wrapInBlockIfNeeded, add one test for when with 3 entries
~~~ refactor WhenTranslator