reset of the toolbar in a multi-byte language(in ie11)

[hyeonmin kim]

I have problems entering Korean text in IE 11 browser. please check it up and let me know what the problem is and how to fix it.

[Case] If you enter the text in the Korean IME mode, there is a problem with the font toolbar is reset it seems that there is the same problem with all multi-byte languages.

[Reproduce steps]

1. using the ie11, Go to ckeditor full demo Web page (​http://ckeditor.com/demo#full)
2. I switch the language to Korean using IME.
3. Delete all contents to make empty.
4. Change the font or font size using the toolbar.
5. Press any key(in Korean input mode)
6. You can see that the toolbar has been reset.

[Jakub Ś]

DUP of #13043.