IR: cleanup expression implementations

Remove unused constructors with descriptors, minimize usages of
secondary constructors and make some properties non-lateinit, fix some
inspections.

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/coroutines/JsSuspendFunctionsLowering.kt

@@ -92,9 +92,9 @@ class JsSuspendFunctionsLowering(ctx: JsIrBackendContext) : AbstractSuspendFunct
             body.endOffset,
             unit,
             COROUTINE_ROOT_LOOP,
-            rootTry,
-            JsIrBuilder.buildBoolean(context.irBuiltIns.booleanType, true)
         ).also {
+            it.condition = JsIrBuilder.buildBoolean(context.irBuiltIns.booleanType, true)
+            it.body = rootTry
             it.label = "\$sm"
         }