Consider dropping browser patch for 26353

I think the patch for legacy/trac#26353 (moved) is not strictly needed, since the speculative connections are blocked when a proxy is configured (here: https://github.com/mozilla/gecko-dev/blob/esr60/netwerk/base/nsIOService.cpp#L1621, and same in 68). So while the speculative requests can be seen in torbutton domain-isolator, they should be dropped before they reach tor client.

I tested by changing the torbutton code to not put all these to the --unknown-- catch-all circuit so that they could be tracked, and while I can see these in logs coming from the domain isolator, there are no corresponding open circuits in the Torbutton INFO: controlPort << getinfo circuit-status logs.

It's always possible that this might change in the future (according to the comments in that file, the reason why the speculative connections are not performed when there is a proxy do not seem so strong). So we might still want the current patch for legacy/trac#26353 (moved) just in case, I'm not sure.