code: function lastIndexOf(searchElement /* , fromIndex = @[*-1] */) {
      // convert -0 to +0
      if (NEGATIVE_ZERO) return $native.apply(this, arguments) || 0;
      var O = toIObject(this);
      var length = toLength(O.length);
      var index = length - 1;
      if (arguments.length > 1) index = Math.min(index, toInteger(arguments[1]));
      if (index < 0) index = length + index;
      for (;index >= 0; index--) if (index in O) if (O[index] === searchElement) return index || 0;
      return -1;
    }
docs: 22.1.3.14 / 15.4.4.15 Array.prototype.lastIndexOf(searchElement [, fromIndex])