Bug 1408005 - Clear gApplicationReputationService in the dtor. r=francois

--HG--
extra : rebase_source : 19582ac4795ab4ab270c00fb8eb065726b183590

toolkit/components/downloads/ApplicationReputation.cpp

@@ -1576,6 +1576,8 @@ ApplicationReputationService::ApplicationReputationService()
 
 ApplicationReputationService::~ApplicationReputationService() {
   LOG(("Application reputation service shutting down"));
+  MOZ_ASSERT(gApplicationReputationService == this);
+  gApplicationReputationService = nullptr;
 }
 
 NS_IMETHODIMP