Get rid of all component builds specific .isolate.

base/base_unittests.isolate

 # Copyright (c) 2012 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=="android" or OS=="linux" or OS=="mac" or OS=="win"', {
       'variables': {
         'isolate_dependency_untracked': [
           'data/',
           'test/data/',
@@ skipping 36 matching lines @@
     }],
     ['OS=="win"', {
       'variables': {
         'isolate_dependency_tracked': [
         ],
       },
     }],
   ],
   'includes': [
     'base.isolate',
-    'base_prefs.isolate',
   ],
 }