IE: Definition list crashes the editor

[Wiktor Walc]

Found in IE8/Quirks, also can be reproduced by setting manually document mode to IE9/Quirks, IE9/IE7 standards, IE8/IE7 standards.

Open the ajax sample, paste the following in source mode:

<dl>
<dt></dt>
<dd></dd>
</dl>

switch to source mode and back. IE shows an alert message:

Stop running this script? 

A script on this page is causing Internet Explorer to run slowly. 
If it continues to run, your computer might become unresponsive.

The same TC till CKEditor 3.5.2 caused an error "Stack overflow at line 26" so it might be a very similar or exactly the same problem as #7290.

It looks like it is enough to adjust IE detection used in #6975.

[Frederico Caldeira Knabben]

DUP of #6975.

[Wiktor Walc]

Hmm it looks I was wrong when reporting it as the issue seems to be gone in the nightly build in IE7, but I still can reproduce it in IE8/quirks.