Firefox: Incorrect cursor position when link is created

[Irina]

To Reproduce:

1. Use ajax sample
2. Type in a word, e.g. test, select it by using Ctrl + A
3. Insert a link
4. Press the right arrow key

Problem: Cursor moves to the very right of the line

5. Continue typing

Problem: Cursor moves to the next line

This issue could be related to ​http://dev.ckeditor.com/ticket/10847

[Jakub Ś]

DUP of #10209.