code: function () {
              var /** @type {?} */ lastRowMax = Math.max.apply(Math, this.tracker);
              // if any of the tiles has a rowspan that pushes it beyond the total row count,
              // add the difference to the rowcount
              return lastRowMax > 1 ? this.rowCount + lastRowMax - 1 : this.rowCount;
          }
docs: Gets the total span of rows occupied by tiles.
  Ex: A list with 1 row that contains a tile with rowspan 2 will have a total rowspan of 2.
  @return {?}