JS: char boxing

js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/metadata/metadataProperties.kt

@@ -50,6 +50,8 @@ var JsParameter.hasDefaultValue: Boolean by MetadataProperty(default = false)
 
 var JsInvocation.typeCheck: TypeCheck? by MetadataProperty(default = null)
 
+var JsInvocation.boxing: Boolean by MetadataProperty(default = false)
+
 /**
  * For function and lambda bodies indicates what declaration corresponds to.
  * When absent (`null`) on body of a named function, this function is from external JS module.