Removed button.close() test because it caused the test framework to hang

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

@@ -1,55 +1,43 b''
 // Test widget button class
 casper.notebook_test(function () {
     index = this.append_cell(
         'from IPython.html import widgets\n' + 
         'from IPython.display import display, clear_output\n' +
         'print("Success")');
     this.execute_cell_then(index);
 
     var button_index = this.append_cell(
         'button = widgets.ButtonWidget(description="Title")\n' +
         'display(button)\n'+
         'print("Success")\n' +
         'def handle_click(sender):\n' +
         '    print("Clicked")\n' +
         'button.on_click(handle_click)');
     this.execute_cell_then(button_index, function(index){
 
         this.test.assert(this.get_output_cell(index).text == 'Success\n', 
             'Create button cell executed with correct output.');
 
         this.test.assert(this.cell_element_exists(index, 
             '.widget-area .widget-subarea'),
             'Widget subarea exists.');
 
         this.test.assert(this.cell_element_exists(index, 
             '.widget-area .widget-subarea button'),
             'Widget button exists.');
 
         this.test.assert(this.cell_element_function(index, 
             '.widget-area .widget-subarea button', 'html')=='Title',
             'Set button description.');
 
         this.cell_element_function(index, 
             '.widget-area .widget-subarea button', 'click');
     });
 
     this.wait(500); // Wait for click to execute in kernel and write output
 
     this.then(function () {
         this.test.assert(this.get_output_cell(button_index, 1).text == 'Clicked\n', 
             'Button click event fires.');
     });
-
-    // Close the button widget asynchronisly.
-    index = this.append_cell('button.close()\n');
-    this.execute_cell(index);
-
-    this.wait(500); // Wait for the button to close.
-
-    this.then(function(){
-        this.test.assert(! this.cell_element_exists(button_index, 
-            '.widget-area .widget-subarea button'),
-            'Widget button doesn\'t exists.');
-    });
 });
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