ev-window.c: Check that we have a document set before accessing it.

Fixes #673.

Author: mtwebster

shell/ev-window.c

@@ -1390,13 +1390,10 @@ ev_window_refresh_window_thumbnail (EvWindow *ev_window)
     gint rotation;
     EvDocument *document = ev_window->priv->document;
 
-    if (document->iswebdocument) {
-        return;
-    }
-
     if (!document || ev_document_get_n_pages (document) <= 0 ||
             ev_document_get_n_pages (document) <= 0 ||
-            !ev_document_check_dimensions (document)) {
+            !ev_document_check_dimensions (document) ||
+            document->iswebdocument) {
         return;
     }