equals(that) {
    return (this.row == that.row && this.column == that.column &&
            this.overflow == that.overflow);
  }
Test if another hterm.RowCol instance is equal to this one.

@param {!hterm.RowCol} that The other hterm.RowCol instance.
@return {boolean} True if both instances have the same row/column, false
    otherwise.