Resolves some issues with Chinese characters in the editor.

[diegoreymendez]

Description

Fixes #811
Alternative solution to #820

Resolves a workaround and improves the code used to change the font size to make it more resilient.

Testing

Test 1

1. Launch the editor
2. Press enter
3. Activate H1
4. Type something with the Chinese keyboard
5. Press enter to accept the marked text
6. Press enter again to go to the next line
7. Type something else.
8. Backspace just before what you wrote in point 7, so it goes up to the H1 line.

Make sure the H1 font is applied to the line you just moved up.

Test 2

1. Launch the editor
2. Press enter
3. Activate H1
4. Type something with the Chinese keyboard
5. Press enter to accept the marked text
6. Keep writing.

Make sure all new characters are still visible.

[jleandroperez]

Beautiful. Just beautiful. Thanks for digging deeeeeper!!!

[diegoreymendez]

Thank you @jleandroperez!