TableCell = function(td, startRow, startCol) {
  this.element = td;
  /** @suppress {strictMissingProperties} Added to tighten compiler checks */
  this.colSpan = parseInt(td.colSpan, 10) || 1;
  /** @suppress {strictMissingProperties} Added to tighten compiler checks */
  this.rowSpan = parseInt(td.rowSpan, 10) || 1;
  this.startRow = startRow;
  this.startCol = startCol;
  this.updateCoordinates_();
}
Class representing a table cell, which may span across multiple
rows and columns
@param {!Element} td This cell's underlying TD or TH element.
@param {number} startRow Index of the row where this cell begins.
@param {number} startCol Index of the column where this cell begins.
@constructor
@final