move promise sync to kernelselector, from notebook

IPython/html/static/notebook/js/notebook.js

@@ -2082,11 +2082,7 @@ define([
         this.notebook_name = utils.url_path_split(this.notebook_path)[1];
         this.events.trigger('notebook_loading.Notebook');
         this.contents.get(notebook_path, {type: 'notebook'}).then(
-            function (data) {
-                that.kernel_selector.loaded.then(
-                    that.load_notebook_success(data)
-                );
-            },
+            $.proxy(this.load_notebook_success, this),
             $.proxy(this.load_notebook_error, this)
         );
     };