remove dependencies to namespace in Tooltip

notebook/static/base/js/namespace.js

@@ -60,6 +60,7 @@ define(function(){
     jglobal('KeyboardManager','notebook/js/keyboardmanager');
     jglobal('Completer','notebook/js/completer');
     jglobal('Notebook','notebook/js/notebook');
+    jglobal('Tooltip','notebook/js/tooltip');
 
     Jupyter.version = "4.0.0.dev";
     Jupyter._target = '_blank';

notebook/static/notebook/js/tooltip.js

@@ -2,10 +2,9 @@
 // Distributed under the terms of the Modified BSD License.
 
 define([
-    'base/js/namespace',
     'jquery',
     'base/js/utils',
-], function(IPython, $, utils) {
+], function($, utils) {
     "use strict";
 
     // tooltip constructor
@@ -319,8 +318,5 @@ define([
         this.text.scrollTop(0);
     };
 
-    // Backwards compatibility.
-    IPython.Tooltip = Tooltip;
-
     return {'Tooltip': Tooltip};
 });