Add markdown to third_party/pkg

pkg/pkg.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.
 
 {
   'targets': [
     {
       'target_name': 'pkg_packages',
       'type': 'none',
       'actions': [
         {
           'action_name': 'make_pkg_packages',
           'inputs': [
             '../tools/make_links.py',
             '<!@(["python", "../tools/list_pkg_directories.py", "."])',
           ],
           'outputs': [
             '<(SHARED_INTERMEDIATE_DIR)/packages.stamp',
           ],
           'action': [
             'python', '../tools/make_links.py',
             '--timestamp_file=<(SHARED_INTERMEDIATE_DIR)/packages.stamp',
             '<(PRODUCT_DIR)/packages',
             '<@(_inputs)',
           ],
         },
+        {
+          'action_name': 'make_third_party_packages',

[Emily Fortuna, 2013/07/08 17:36:30]

There may (I hope?) be a less verbose way to do this (adding a line around line
15?), but I wasn't having success doing so. 

[Bob Nystrom, 2013/07/08 17:41:13]

Yeah, Peter might be able to help here. Gyp is mostly dark magic to me.

[ahe, 2013/07/11 10:19:30]

I've filed https://code.google.com/p/dart/issues/detail?id=11779 so I don't
forget.

+          'inputs': [
+            '../tools/make_links.py',
+            '<!@(["python", "../tools/list_pkg_directories.py", '
+                '"../third_party/pkg"])',
+          ],
+          'outputs': [
+            '<(SHARED_INTERMEDIATE_DIR)/third_party_packages.stamp',
+          ],
+          'action': [
+            'python', '../tools/make_links.py',
+            '--timestamp_file=<(SHARED_INTERMEDIATE_DIR)/third_party_packages.'
+                'stamp',
+            '<(PRODUCT_DIR)/packages',
+            '<@(_inputs)',
+          ],
+        },
       ],
     }
   ],
 }