Accented letters workaround for WhatsApp on Firefox Linux

When running under Firefox on Linux, WhatsApp Web inputs don’t accept letters entered using dead keys as the first letter in the input box. This script tries to fix this. This script was written by trial and error, so I’m not sure if this is the most correct fix, but at least for me it does work.

It eats compositionstart and compositionend events, and eats any input event that happens between a compositionstart and a compositionend.

For an example of the problem this script tries to fix:

https://forum.manjaro.org/t/whatsapp-web-deleting-letter-that-starts-with-accent/119772