Browser 10.0.2

A quick check in the MIUI forum (http://en.miui.com), and I found quite a few threads that have the browser APK file (installation file) to download. You might want to check them out yourself, and download the apk file and install it on your phone.

Alternatively, you can backup all your data and settings, and then do do a factory reset.

A factory reset should give you back all the pre-installed apps including the Browser app.