为什么Firefox错误地显示带有colspan和rowspan的表？

Question

该表在Chrome和Opera中显示得很好，在Firefox中根本没有...我该如何解决？

Screenshot

代码：https://jsfiddle.net/Hamsterman/6zth1mjv/

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<table>
  <tr>
    <td colspan="2" rowspan="2"></td>
    <td colspan="2" rowspan="2"></td>
    <td colspan="2" rowspan="2"></td>
    <td colspan="2" rowspan="2"></td>
    <td colspan="2" rowspan="2"></td>
  </tr>
  <tr></tr>
  <tr>
    <td colspan="2" rowspan="2"></td>
    <td colspan="3" rowspan="3"></td>
    <td colspan="3" rowspan="3"></td>
    <td colspan="2" rowspan="2"></td>
  </tr>
  <tr></tr>
  <tr>
    <td colspan="2" rowspan="2"></td>
    <td colspan="2" rowspan="2"></td>
  </tr>
  <tr>
    <td colspan="3" rowspan="3"></td>
    <td colspan="3" rowspan="3"></td>
  </tr>
  <tr>
    <td colspan="2" rowspan="2"></td>
    <td colspan="2" rowspan="2"></td>
  </tr>
  <tr></tr>
  <tr>
    <td colspan="2" rowspan="2"></td>
    <td colspan="2" rowspan="2"></td>
    <td colspan="2" rowspan="2"></td>
    <td colspan="2" rowspan="2"></td>
    <td colspan="2" rowspan="2"></td>
  </tr>
  <tr></tr>
</table>

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