Remove rule 436089, as the character encoding depends on the website being used.

Furter usage on different webapps proved my point was incorrect about AJAX, so remove this particular rule.
Mediapartners-Google is no longer coming only from googlebot IPs.

But it's still only Google, so don't remove the filtering.
Add a validation rule for Adsbot too.
Remove a check for sdch presence for Chrome.

Version 37 of Chromium no longer supports sdch.