Add step generator protocol, remove annotated_checkout, remove script.

scripts/slave/recipes_test/toolkit.py

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Test inputs for recipes/toolkit.py"""
 
 def basic_test(api):
   return {
     'build_properties': api.tryserver_build_properties(
       repository="https://github.com/toolkitchen/toolkit"
     ),
+    'test_data': {
+      'gen step(gen_steps.py)': (0, [
+        {'name': 'bogus', 'cmd': ['bogus.py', '--arg']}
+      ])
+    }
   }