bug #63529. Added a null-pointer check in nsWebShell::OnStateChange(...)

git-svn-id: svn://10.0.0.236/trunk@84012 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/docshell/base/nsWebShell.cpp

@@ -894,6 +894,10 @@ NS_IMETHODIMP
 nsWebShell::OnStateChange(nsIWebProgress *aProgress, nsIRequest *aRequest,
                           PRInt32 aStateFlags, nsresult aStatus)
 {
+  if (!aRequest) {
+    return NS_OK;
+  }
+
   if (aStateFlags & STATE_IS_DOCUMENT) {
     nsCOMPtr<nsIWebProgress> webProgress(do_QueryInterface(mLoadCookie));