Revert of Fix sbox_validation_tests & Make isolate_driver.py include the executable itself

ui/accessibility/accessibility_unittests.isolate

 # Copyright (c) 2014 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.
 {
   'conditions': [
     ['OS=="linux" or OS=="mac" or OS=="win"', {
       'variables': {
         'command': [
           '<(PRODUCT_DIR)/accessibility_unittests<(EXECUTABLE_SUFFIX)',
         ],
+        'files': [
+          '<(PRODUCT_DIR)/accessibility_unittests<(EXECUTABLE_SUFFIX)',
+        ],
       },
     }],
   ],
   'includes': [
     '../../base/base.isolate',
   ],
 }