Bug 720554 - Use fatal assertion and check thread in History::Shutdown. r=mak.

--HG--
extra : rebase_source : 36b610364f9e9150fcfbf6cfe26834a1b87f81f1

toolkit/components/places/History.cpp

@@ -1750,7 +1750,8 @@ History::GetDBConn()
 void
 History::Shutdown()
 {
-  NS_ASSERTION(!mShuttingDown, "Shutdown was called more than once!");
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!mShuttingDown && "Shutdown was called more than once!");
 
   mShuttingDown = true;