Add comments emphasizing the order of steps in widget box remove() methods

IPython/html/static/widgets/js/widget_box.js

@@ -79,6 +79,9 define([
         },
         
         remove: function() {
+            // We remove this widget before removing the children as an optimization
+            // we want to remove the entire container from the DOM first before
+            // removing each individual child separately.
             BoxView.__super__.remove.apply(this, arguments);
             this.children_views.remove();
         },

IPython/html/static/widgets/js/widget_selectioncontainer.js

@@ -128,6 +128,9 define([
         },
         
         remove: function() {
+            // We remove this widget before removing the children as an optimization
+            // we want to remove the entire container from the DOM first before
+            // removing each individual child separately.
             AccordionView.__super__.remove.apply(this, arguments);
             this.children_views.remove();
         },
@@ -252,6 +255,9 define([
         },
         
         remove: function() {
+            // We remove this widget before removing the children as an optimization
+            // we want to remove the entire container from the DOM first before
+            // removing each individual child separately.
             TabView.__super__.remove.apply(this, arguments);
             this.children_views.remove();
         },