Set Facet.{itemCount,checkedCount}.

@@ -30,6 +30,8 @@ define(function(require) {
     var Facet = Backbone.Model.extend({
         defaults: function defaults() {
             return {
+                itemCount: 0,
+                checkedCount: 0,
                 checkedKeys: [],
                 formName: null,
                 query: null,
@@ -67,6 +69,7 @@ define(function(require) {
                     try {
                         this.set({
                             all: checkedCount === 0,
+                            checkedCount: checkedCount,
                             checkedKeys: checkedKeys,
 
                         });
@@ -120,6 +123,7 @@ define(function(require) {
                         });
                         this.set({
                             all: checkedCount === 0,
+                            checkedCount: checkedCount,
                         });
                     } finally {
                         skipCallback = null;
@@ -180,12 +184,19 @@ define(function(require) {
                 items.sort();
             }, this);
 
-            this.set('items', new ItemCollection([]));
+            var items = new ItemCollection([]);
+            this.set('items', items);
             this.set('comparator', options.comparator, {silent: true});
             this.trigger('change:comparator');
-            this.get('items').on('item-change', function(model, value, options) {
+            items.on('item-change', function(model, value, options) {
                 this.trigger('item-change', null, null, options);
             }, this);
+            items.on('update', function(model, value, options) {
+                var items = this.get('items');
+                this.set({
+                    itemCount: items.length,
+                });
+            }, this);
             this.facetType = options.facetType;
             this.facetStats = options.facetStats;
             this.other = options.other;