Bug 821534 - move mozilla::PoisonWrite one line earlier. r=ehsan.

xpcom/build/nsXPComInit.cpp

@@ -616,11 +616,11 @@ ShutdownXPCOM(nsIServiceManager* servMgr)
     // Release the directory service
     NS_IF_RELEASE(nsDirectoryService::gService);
 
-    nsCycleCollector_shutdown();
-
     SAMPLE_MARKER("Shutdown xpcom");
     mozilla::PoisonWrite();
 
+    nsCycleCollector_shutdown();
+
     if (moduleLoaders) {
         bool more;
         nsCOMPtr<nsISupports> el;