Uncommented parent/child test that was failing

IPython/html/tests/casperjs/test_cases/widgets.js

@@ -280,9 +280,9 b' casper.notebook_test(function () {'
             '.widget-area .widget-subarea .widget-container'),
             'Parent container not displayed.');
 
-        // this.test.assert(this.cell_element_exists(index, 
-        //     '.widget-area .widget-subarea button'),
-        //     'Child displayed.');
+        this.test.assert(this.cell_element_exists(index, 
+            '.widget-area .widget-subarea button'),
+            'Child displayed.');
     });
 });