remove reverse dependency in Page

notebook/static/base/js/namespace.js

@@ -23,6 +23,7 @@ define(function(){
     Jupyter.Kernel = require('services/kernels/kernel').Kernel;
     Jupyter.Session = require('services/kernels/session').Session;
     Jupyter.LoginWidget = require('auth/js/loginwidget').LoginWidget
+    Jupyter.Page = require('base/js/page').Page;
 
     Jupyter.version = "4.0.0.dev";
     Jupyter._target = '_blank';

notebook/static/base/js/page.js

@@ -2,10 +2,9 @@
 // Distributed under the terms of the Modified BSD License.
 
 define([
-    'base/js/namespace',
     'jquery',
     'base/js/events',
-], function(IPython, $, events){
+], function($, events){
     "use strict";
 
     var Page = function () {
@@ -59,7 +58,5 @@ define([
         $('div#site').height($(window).height() - $('#header').height());
     };
 
-    // Register self in the global namespace for convenience.
-    IPython.Page = Page;
     return {'Page': Page};
 });