Bug 1523795: Make temp copy of query->now to avoid access after query has been moved. r=ng

Differential Revision: https://phabricator.services.mozilla.com/D19380

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

media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp

@@ -2993,9 +2993,10 @@ RefPtr<RTCStatsQueryPromise> PeerConnectionImpl::ExecuteStatsQuery_s(
     transportId = query->transportId;
   }
   auto report = std::move(query->report);
+  auto now = query->now;
 
   return aTransportHandler
-      ->GetIceStats(transportId, query->now, std::move(report))
+      ->GetIceStats(transportId, now, std::move(report))
       ->Then(
           GetMainThreadSerialEventTarget(), __func__,
           [query = std::move(query)](