They must be neutral in the sense that they should not make specific rules for specific services. We have seen in a previous hn post that webkit has specific rules for quite some websites, now firefox has these replacements for some javascript codes.

This is wrong and will break things: if there are bad behaviors, like the cookie usage, the rules should be changed to prevent it, that's great, but having ifs and replacing selected scripts is a horrible way to go.

First reason for this is that obviously Google will try to go around that rule and change it's script. Or some nasty tricks like using script proxies, ... Second is that if Google Analytics is blocked by name, then other tracking services will take the space, and users will loose anyway.

Exactly this, web-browsers should look after the user, and should protect the user against webbrowser-exploits e.g. 1px png tracking images and cookies.

Yeah somehow I think you would have a different opinion if Chrome offered users a performance boost only on Google owned websites.