IE: error when selecting contents with SHIFT+Arrow

[Jakub Ś]

To reproduce:

1. Clear editor contents
2. Write a letter
3. Press ENTER twice
4. Write a letter again
5. Activate 'source view' and go back (without this there will be no script error)
6. Place the cursor on top-left position - before first letter - at the beginning of editor content area.
7. Press SHIFT+'arrow down' twice

Result: JavaScript error is thrown.
Ticket has been reproducible in IE8 and IE9 from CKEditor 3.5.1

The error comes from the core\dom\node.js from the getPosition function where the this.$ is undefined. Seems that this object has nothing to do with the underlying DOM object.

NOTES:
From CKEditor 3.5.1 till 3.6.3 the error was
Message: 'length' is null or not an object
Line: 632
URI: /3.6.3/ckeditor/_source/plugins/selection/plugin.js

From CKEditor 3.6.3 rev. [7415] the error has changed: Message: 'compareDocumentPosition' is null or not an object
Line: 430
URI: /3.6.3/ckeditor/_source/core/dom/node.js