[infra] Begin removing gyp

utils/dartdoc/dartdoc.gyp

-# Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
-# for details. All rights reserved. Use of this source code is governed by a
-# BSD-style license that can be found in the LICENSE file.
-
-{
-  'targets': [
-    {
-      'target_name': 'dartdoc',
-      'type': 'none',
-      'dependencies': [
-        '../../runtime/dart-runtime.gyp:dart',
-      ],
-      'actions': [
-        {
-          'action_name': 'generate_dartdoc_snapshot',
-          'inputs': [
-            '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)dart<(EXECUTABLE_SUFFIX)',
-            '../../sdk/lib/_internal/sdk_library_metadata/lib/libraries.dart',
-            '<!@(["python", "../../tools/list_dart_files.py", "relative", '
-                '"../../third_party/pkg/dartdoc"])',
-          ],
-          'outputs': [
-            '<(SHARED_INTERMEDIATE_DIR)/dartdoc.dart.snapshot',
-          ],
-          'action': [
-            '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)dart<(EXECUTABLE_SUFFIX)',
-            '--packages=../../.packages',
-            '--snapshot=<(SHARED_INTERMEDIATE_DIR)/dartdoc.dart.snapshot',
-            '../../third_party/pkg/dartdoc/bin/dartdoc.dart',
-          ],
-        },
-      ],
-    },
-  ],
-}