function decode( str, enc ) {
	// Check if we need to re-decode the string to something other than 'utf8'...
	if ( enc === 'utf8' || enc === 'buffer' ) {
		return str;
	}
	str = string2buffer( str );
	if ( enc ) {
		return str.toString( enc );
	}
	return str.toString();
}
Re-decodes a UTF-8 string according to a specified encoding.

@private
@param {string} str - UTF-8 string to decode
@param {string} enc - string encoding
@returns {string} decoded string