docs: public static Object callIterator(Object obj, Context cx, Scriptable scope)
      {
          final Callable getIterator =
                  ScriptRuntime.getElemFunctionAndThis(obj, SymbolKey.ITERATOR, cx, scope);
          final Scriptable iterable = ScriptRuntime.lastStoredScriptable(cx);
          return getIterator.call(cx, scope, iterable, ScriptRuntime.emptyArgs);
      }