Rename all isolate_dependency_* to files.

mojo/mojo_python_unittests.isolate

 # Copyright 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"', {
       'variables': {
         'command': [
           'tools/run_mojo_python_bindings_tests.py',
           '--build-dir=<(PRODUCT_DIR)',
         ],
-        'isolate_dependency_tracked': [
+        'files': [
+          '<(PRODUCT_DIR)/gen/mojo/public/interfaces/bindings/tests/',
+          '<(PRODUCT_DIR)/python/',
+          'python/tests/',
           'tools/pylib/mojo_python_tests_runner.py',
           'tools/run_mojo_python_bindings_tests.py',
         ],
-        'isolate_dependency_untracked': [
-          'python/tests/',
-          '<(PRODUCT_DIR)/gen/mojo/public/interfaces/bindings/tests/',
-          '<(PRODUCT_DIR)/python/',
-        ],
       },
     }],
   ],
 }