Don't run xfail tests

test/python_tests.txt

@@ -466,7 +466,7 @@ test_types
 test_typing unknown
 test_ucn
 test_unary
-test_unicode
+test_unicode  crash
 test_unicode_file
 test_unicode_file_functions
 test_unicode_identifiers

test/test_python.py

@@ -290,9 +290,8 @@ def test_run_core_python_test(python_test, selenium, request):
 
     if ('crash' in error_flags or
             'crash-' + selenium.browser in error_flags):
-        request.applymarker(pytest.mark.xfail(
-            run=False, reason='known failure with code "{}"'
-                              .format(','.join(error_flags))))
+        pytest.xfail(reason='known failure with code "{}"'
+                            .format(','.join(error_flags)))
 
     selenium.load_package('test')
     try: