Bug 1595572 - Remove NetworkConnectivityService.cpp MOZ_ASSERT("unknown request") r=kershaw

In a corner case race we might receive a notification from the wrong channel.
- mIPv4Channel is loading and calls nsHttpChannel::DoAuthRetry(NS_OK)
- RecheckDNS() is called and mIPv4Channel gets replaced
  we call Cancel for the old channel
- nsHttpChannel::ContinueDoAuthRetry is called, which calls OnStopRequest
  for the old channel
- We hit the assertion because we get the call for the wrong channel

Differential Revision: https://phabricator.services.mozilla.com/D61165

--HG--
extra : moz-landing-system : lando

netwerk/base/NetworkConnectivityService.cpp

@@ -287,8 +287,6 @@ NetworkConnectivityService::OnStopRequest(nsIRequest* aRequest,
   } else if (aRequest == mIPv6Channel) {
     mIPv6 = status;
     mIPv6Channel = nullptr;
-  } else {
-    MOZ_ASSERT(false, "Unknown request");
   }
 
   if (!mIPv6Channel && !mIPv4Channel) {