Unexpected list structure after insert list item

[Martin]

1. Crete list like this:

<ul>

<li>a

<ul>

<li>[b</li> <li>c

<ul>

<li>d]</li>

</ul>

</li>

</ul> </li> <li>e</li> <li>f</li>

</ul>

2. Create selection form 'b' to 'd' item as in example
   

3. Type some char e.g. 'a'
   

Expected result

New char will be replacing 'b' item and rest of selection will be removed

Actual result

I don`t see typed char and list has strange structure. Diffrent structure depends on browsers.

[Garry Yao]

Similar with #6688.