Simplify LocalDeclarationsLowering, support declaration pop up via separate lower

1. Scheme of capturing local variables not touched
 2. Lowered local functions are transposed to the nearest class (including local) or file
 3. Local classes are also transpose to the nearest class (including local) or file

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt

@@ -179,6 +179,13 @@ private val localDeclarationsLoweringPhase = makeJsModulePhase(
     prerequisite = setOf(sharedVariablesLoweringPhase, localDelegatedPropertiesLoweringPhase)
 )
 
+private val localClassExtractionPhase = makeJsModulePhase(
+    ::LocalClassPopupLowering,
+    name = "LocalClassExtractionPhase",
+    description = "Move local declarations into nearest declaration container",
+    prerequisite = setOf(localDeclarationsLoweringPhase)
+)
+
 private val innerClassesLoweringPhase = makeJsModulePhase(
     ::InnerClassesLowering,
     name = "InnerClassesLowering",
@@ -372,6 +379,7 @@ val jsPhases = namedIrModulePhase(
             sharedVariablesLoweringPhase then
             localDelegatedPropertiesLoweringPhase then
             localDeclarationsLoweringPhase then
+            localClassExtractionPhase then
             innerClassesLoweringPhase then
             innerClassConstructorCallsLoweringPhase then
             propertiesLoweringPhase then