1. Deprecated("Internal Use Only")
dynamic unwrap_jso(dartClass_instance)

Used by callMethod to get the JS object for each argument passed if the argument is a Dart class instance that delegates to a DOM object. See wrap_jso defined in dart:html.

Source 

@Deprecated("Internal Use Only")
unwrap_jso(dartClass_instance) {
  if (dartClass_instance is JSObject &&
      dartClass_instance is! JsObject) return dartClass_instance.blink_jsObject;
  else return dartClass_instance;
}