"#element".tooltip is not a function on home page fixed. (#6070)

* Fixed missing $ symbol and cleaned up code a bit.

notebook/templates/tree.html

@@ -215,10 +215,9 @@ data-server-root="{{server_root}}"
 
 {% block script %}
     {{super()}}
+    <script src="{{ static_url("tree/js/main.min.js") }}" type="text/javascript" charset="utf-8"></script>
+
     <script type="text/javascript">
-      ('#element').tooltip('enable')
+      $('#element').tooltip('enable')
     </script>
-
-<script src="{{ static_url("tree/js/main.min.js") }}" type="text/javascript" charset="utf-8"></script>
-
 {% endblock %}