Fix for bug 216474 - Browser crashes in password manager. Ensure that we don't crash or overwrite variables used to hold valid password data fields with null. r=bryner

toolkit/components/passwordmgr/base/nsPasswordManager.cpp

@@ -621,21 +621,26 @@ nsPasswordManager::OnStateChange(nsIWebProgress* aWebProgress,
 
     nsCOMPtr<nsIForm> form = do_QueryInterface(formNode);
     SignonDataEntry* firstMatch = nsnull;
-    nsCOMPtr<nsIDOMHTMLInputElement> userField, passField;
+    nsCOMPtr<nsIDOMHTMLInputElement> userField, passField;
+    nsCOMPtr<nsIDOMHTMLInputElement> temp;
 
     for (SignonDataEntry* e = hashEnt->head; e; e = e->next) {
       
       nsCOMPtr<nsISupports> foundNode;
-      form->ResolveName(e->userField, getter_AddRefs(foundNode));
-      userField = do_QueryInterface(foundNode);
-
-      if (!userField)
+      form->ResolveName(e->userField, getter_AddRefs(foundNode));
+      temp = do_QueryInterface(foundNode);
+
+      if (temp)
+        userField = temp;
+      else
         continue;
 
-      form->ResolveName(e->passField, getter_AddRefs(foundNode));
-      passField = do_QueryInterface(foundNode);
-
-      if (!passField)
+      form->ResolveName(e->passField, getter_AddRefs(foundNode));
+      temp = do_QueryInterface(foundNode);
+
+      if (temp)
+        passField = temp;
+      else
         continue;
 
       if (firstMatch) {