Possibly one could also proxy every proxied domain to a separate subdomain to avoid that problem.
E.g. example.org.my-https-proxy.example and annoying-advertisement.example.my-https-proxy.example
Posted Sep 24, 2011 19:51 UTC (Sat) by butlerm (subscriber, #13312)
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The problem with doing that if that you have separate HTTPS startup latency for every separate ad provider, which on some sites seems to be half a dozen or more. If you can safely proxy advertising content, pages will load much faster.
If advertisers just can't live without Javascript, perhaps the W3C could standardize on a technique to sandbox scripts originating from the same domain, even running on the same page.