code: static boolean isIThenableSubtype(JSType type) {
      if (type.isTemplatizedType()) {
        TemplatizedType ttype = type.toMaybeTemplatizedType();
        return ttype.getTemplateTypeMap().hasTemplateKey(ttype.registry.getThenableValueKey());
      }
      return false;
    }
docs: Determines if the specified type is exempt from standard invariant templatized typing rules.