[gn] Move build to gypfiles

gypfiles/isolate.gypi

 # Copyright 2015 the V8 project authors. All rights reserved.
 # 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.
 
 # This file is meant to be included into a target to provide a rule
 # to "build" .isolate files into a .isolated file.
 #
 # To use this, create a gyp target with the following form:
 # 'conditions': [
 #   ['test_isolation_mode != "noop"', {
 #     'targets': [
 #       {
 #         'target_name': 'foo_test_run',
 #         'type': 'none',
 #         'dependencies': [
 #           'foo_test',
 #         ],
 #         'includes': [
-#           '../build/isolate.gypi',
+#           '../gypfiles/isolate.gypi',
 #         ],
 #         'sources': [
 #           'foo_test.isolate',
 #         ],
 #       },
 #     ],
 #   }],
 # ],
 #
 # Note: foo_test.isolate is included and a source file. It is an inherent
@@ skipping 60 matching lines @@
           ],
         }, {
           'action': [
             '--config-variable', 'msvs_version=0',
           ],
         }],
       ],
     },
   ],
 }