Bug 239572: nullcheck before calling CallQueryInterface

r/sr=jst a=chofmann

content/base/src/nsXMLHttpRequest.cpp

@@ -246,7 +246,9 @@ GetDocumentFromScriptContext(nsIScriptContext *aScriptContext)
   if (window) {
     nsCOMPtr<nsIDOMDocument> domdoc;
     window->GetDocument(getter_AddRefs(domdoc));
-    (void) CallQueryInterface(domdoc, &doc);
+    //if (domdoc) {
+      CallQueryInterface(domdoc, &doc);
+    //}
   }
   return doc;
 }