code: function(cb) {
      if (IndexedDB.deleteDatabase) {
        var request = IndexedDB.deleteDatabase(this.setup.database);
        // It's always in an order of onblocked -> onsuccess,
        // ignoring other handlers, for now.
        request.onsuccess = function(event) {
          if (isFunction(cb)) return cb(null, event.target.result);
        };
        request.onerror = function(event) {
        };
        request.onblocked = function(event) {
        };
        request.onversionchange = function(event) {
        };
      }
    }
docs: If deleting database is provided by implementation,
  delete the database used with current setup.
  
  @param {Function} callback - gets one argument `(err)`,
  if there is no error `err` is null.
  
  TODO: correct success, blocked, versionchange handling,
  current spec is unclear and outcome is not usable,
  thus using only the `onsuccess` handler.