static inline bool
IsEllipsis(jsval v)
{
  if (!JSVAL_IS_STRING(v))
    return false;
  JSString* str = JSVAL_TO_STRING(v);
  if (JS_GetStringLength(str) != 3)
    return false;
  jschar* chars = JS_GetStringChars(str), dot('.');
  return (chars[0] == dot &&
          chars[1] == dot &&
          chars[2] == dot);
}