Stop generating package docs from docgen

utils/apidoc/docgen.gyp

 # Copyright (c) 2012, 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.
 
 {
   'variables' : {
     'script_suffix%': '',
   },
   'conditions' : [
     ['OS=="win"', {
@@ skipping 60 matching lines @@
           'outputs': [
             '<(PRODUCT_DIR)/api_docs/docgen/index.json',
           ],
           'action': [
             'python',
             '../../tools/only_in_release_mode.py',
             '<@(_outputs)',
             '--',
             '<(PRODUCT_DIR)/dart-sdk/bin/docgen<(script_suffix)',
             '--out=<(PRODUCT_DIR)/api_docs/docgen',
-            '--include-sdk',
-            '--no-include-dependent-packages',
-            '--package-root=<(PRODUCT_DIR)/packages',
-            '--exclude-lib=async_helper',
-            '--exclude-lib=compiler',
-            '--exclude-lib=dart2js_incremental',
-            '--exclude-lib=docgen',
-            '--exclude-lib=expect',
-            '--exclude-lib=try',
-            '../../pkg'
+            '--parse-sdk',
+            '--exclude-lib=metadata',
+            '.'
           ],
           'message': 'Running docgen: <(_action)',
         },
       ],
     }
   ],
 }