First install this Opera add-on:
https://addons.opera.com/en/extensions/details/download-chrome-extension-9/?display=en
then install avast online security from Chrome Web Store:
https://chrome.google.com/webstore/detail/avast-online-security/gomekmidlodglbbmalcneegieacbdmki
I tried it in Opera Developer 18 and it is working fine.
Edit:
Actually it doesn’t work anymore.Previous version of avast online security worked fine in Opera Developer.Sorry.