delete table column should consider about the nested table case

[brooks]

where,this is a update for 5577 5577,Garry said:
'As a side note for 5418 this change, in the future please use instead the following way to iterating over table cells and rows, as table.getElementsByTagName('tr') would returns nested table rows also. ​http://msdn.microsoft.com/en-us/library/ms537443(VS.85).aspx'[[BR]]

[brooks]

fixed with 5438 5438