fix(KT-49225): remove unnecessery boxing.

js/js.translator/testData/box/export/defaultInlineClassConstructorParam.kt

@@ -0,0 +1,16 @@
+// KT-49225
+// RUN_PLAIN_BOX_FUNCTION
+// IGNORE_BACKEND: JS
+
+// MODULE: lib
+// FILE: lib.kt
+value class Koo(val koo: String = "OK")
+
+@JsExport
+class Bar(val koo: Koo = Koo())
+
+// MODULE: main(lib)
+// FILE: main.js
+function box() {
+    return new main.Bar().koo;
+}