js: Update permalinks and undo/redo buttons when loading

Without this, the "Undo" button ends up greyed even though it actually
works.  I'm not sure about whether updating the permalinks is necessary:
maybe we don't need that in new_game() either.

emcc.c

@@ -882,6 +882,8 @@ void load_game(const char *buffer, int len)
         select_appropriate_preset();
         resize();
         midend_redraw(me);
+        update_permalinks();
+        update_undo_redo();
     }
 }