Bug 1904238 - Don't copy over https-first and -only flags on http redirects r=maltejur

To not unexpectedly downgrade requests that weren't upgraded via HTTPS-First.

From the added tests only the http redirect test cases start passing
with this patch. META and JS redirect already pass before this patch.

Differential Revision: https://phabricator.services.mozilla.com/D215214

netwerk/protocol/http/HttpBaseChannel.cpp

@@ -4437,6 +4437,11 @@ already_AddRefed<nsILoadInfo> HttpBaseChannel::CloneLoadInfoForRedirect(
       newLoadInfo->SetLoadTriggeredFromExternal(false);
     }
     newLoadInfo->ResetSandboxedNullPrincipalID();
+
+    // Reset HTTPS-first and -only status on http redirect. To not unexpectedly
+    // downgrade requests that weren't upgraded via HTTPS-First (Bug 1904238).
+    Unused << newLoadInfo->SetHttpsOnlyStatus(
+        nsILoadInfo::HTTPS_ONLY_UNINITIALIZED);
   }
 
   newLoadInfo->AppendRedirectHistoryEntry(this, isInternalRedirect);