Unable to select cells using mouse, when row/columns were removed by merge

[marwinpl]

When you merge cells, causing some columns or rows to be removed, the table retains the original colspan and rowspan settings. As a result, you cannot select cells using the mouse.

Steps to reproduce:

1. Create default table 3x3
2. Merge all cells in column 1
3. Merge all cells in column 2
4. Merge column 1 and 2
   // at this stage you should have table 2x3 (but first cell will have colspan=2)
5. Merge 2nd and 3rd cell in last column.
   // at this stage first cell have rowspan=3 and colspan=2, when table in fact is 2x2.

When now you will try to select cells using mouse from bottom-right it will not work. Trying to select from top-left sometimes work partially, sometimes correct depend on the mouse movement. Selecting by keyboard works fine.

Example of table after merging I described in steps:

HTML structure before merge:

<table>
    <tr>
        <td></td>
        <td></td>
        <td></td>
    </tr>
    <tr>
        <td></td>
        <td></td>
        <td></td>
    </tr>
    <tr>
        <td></td>
        <td></td>
        <td></td>
    </tr>
</table>

And after merge:

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

    </tr>
</table>