Implement DOMException #21

exception DOMException {
  unsigned short   code;
};

// ExceptionCode
const unsigned short      INDEX_SIZE_ERR     = 1;
const unsigned short      DOMSTRING_SIZE_ERR = 2;
const unsigned short      HIERARCHY_REQUEST_ERR = 3;
const unsigned short      WRONG_DOCUMENT_ERR = 4;
const unsigned short      INVALID_CHARACTER_ERR = 5;
const unsigned short      NO_DATA_ALLOWED_ERR = 6;
const unsigned short      NO_MODIFICATION_ALLOWED_ERR = 7;
const unsigned short      NOT_FOUND_ERR      = 8;
const unsigned short      NOT_SUPPORTED_ERR  = 9;
const unsigned short      INUSE_ATTRIBUTE_ERR = 10;