) {
        return Polymer.IronA11yKeysBehavior.keyboardEventMatchesKeys(
          event, 'pageup pagedown home end up left down right');
      },

      _hasCachedLockedElement: function(element) {
        return this._lockedElementCache.indexOf(element) > -1;
      },

      _hasCachedUnlockedElement: function(element) {
        return this._unlockedElementCache.indexOf(element) > -1;
      },

      _composedTreeContains: function(element, child) {
        // NOTE(cdata): This method iterates over conte