Fix for crash if -moz-binding points to an invalid file.

r=jst, sr=hyatt, b=81941

--pete

content/xbl/src/nsXBLService.cpp

@@ -310,6 +310,7 @@ nsXBLStreamListener::OnStopRequest(nsIRequest* request, nsISupports* aCtxt, nsre
       nsXBLBindingRequest::Destroy(mXBLService->mPool, req);
     }
 
+    mBindingRequests.Clear();
     mDocument = nsnull;
     mBindingDocument = nsnull;
   }