Problems in IE when pressing CRTL+B on bolded text

[Jakub Ś]

This ticket was first reported in forum ​http://cksource.com/forums/viewtopic.php?f=11&t=22912

To reproduce:

1. Open api sample and clean CKEditor contents
2. Press bold button and type 'Testing statement'
3. Place cursor here 'Testing s^tatement'
4. In insertHTML text-area paste <p>sample to be inserted by insertHTMl</p> and press 'Insert HTML'. Result should be as in finding2.JPG.
5. Select using a mouse word 'statement' and what was pasted between it. See finding3.JPG.
6. Press CRTL+B one or two times.

If you press CRTL+B two times it will cause JS error in IE8 and IE9:
IE8 yields:
Message: 'null' is empty or not an object
Line: 63
URI: /_source/core/dom/walker.js

IE9 yields:
Message: Can't get property „getParent”: Object is null or undefined
Line: 1568
URI: /_source/core/dom/range.js

This is reproducible from CKE 3.4. Before 3.4 there was no error but unbolding was weird. Some parts of text were duplicated

If you press CRTL+B once than in IE6 and IE7, the phrase 'sample to be inserted by insertHTML' gets unboladed and jumps up.

This is reproducible form CKE 3.6.1 rev [6919]. Before this revision JS error was thrown.