It would be convenient to think that because we live in a world where people’s browsers are regularly updating, that we live in a world where the web is in a reliable state.
The web is a continually moving target. It probably changed in the time it took me to write this. If you work with web stuff you need to embrace this fact. It will be the only constant in your career.
Do not panic:
On the web progressive enhancement is and will always be, the methodology of choice. It makes your site robust to the shifting sands of the web front end.