Yeah, you can’t. You’ll have to change the locale Chrome is running in. And if you’re on Linux you can’t do it in the browser – it looks at your environment variables.
So if you want your dates in nice ISO-8601 standard (or if you want to run Chrome in Swedish but the rest of your OS in English) you have to set up the environment just for Chrome.
Said and done, I changed my application launcher to run
/bin/sh -c 'LANGUAGE=sv_SE.UTF-8 && /usr/bin/google-chrome-stable'