rowspan didn't decrease when remove cell from other column

[bryan]

while editing table, if there's a rowspan attribute on cell in one column, then you remove a cell from another column, the value should decrease but it didn't.

Steps to reproduce :

1. create a table (in my case 3 rows 2 columns)
2. make top left cell merge down twice (which result in a <td> spanned 3 row)
3. remove the middle cell from another column
4. view source

Browser name and OS : Chrome 23.0.1271.101 on Mac OS X 10.8.2

Tested on release and nightly build.

[Jakub Ś]

DUP of #6618.

There are also two similar tickets #2859 and #8666