Quill editor: fix Korean character merging bug

[lakesare]

From the email:

Hi, I wanted to let you know about an error I caught, I still haven't had time to do a dev environment yet and may look into it myself, but I often study Korean, and when I try to input characters, they get separated and don't form the character (see screenshot, for example those three characters should form one unit, and not be spaced out separately. I don't know what is causing it but it really slows down input of info into the boxes. It may be the same for other languages and characters too.

Is there a similar issue with the indian alphabet? The way to tackle this issue is basically to google something along the lines of 'Quill' + 'korean', and then see if any solutions work for us. Bonus points if you find how to test the solution.