create dartdoc snapshot, add to dart-sdk. Also add resources needed to run dartdoc from the sdk.

DEPS

 # 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.
 
 vars = {
   # The dart_root is the root of our sdk checkout. This is normally
   # simply sdk, but if using special gclient specs it can be different.
   "dart_root": "sdk",
 
   # The svn location to pull out dependencies from
@@ skipping 31 matching lines @@
   "args_tag": "@0.13.0",
   "async_tag": "@1.2.0",
   "barback_tag" : "@0.15.2+6",
   "charcode_tag": "@1.1.0",
   "chrome_rev" : "@19997",
   "clang_rev" : "@28450",
   "cli_util_tag" : "@0.0.1+2",
   "collection_rev": "@1da9a07f32efa2ba0c391b289e2037391e31da0e",
   "crypto_rev" : "@2df57a1e26dd88e8d0614207d4b062c73209917d",
   "csslib_tag" : "@0.12.0",
-  "dartdoc_tag" : "@v0.5.0",
+  "dartdoc_tag" : "@v0.5.0+3",
   "dart_services_rev" : "@7aea2574e6f3924bf409a80afb8ad52aa2be4f97",
   "dart_style_tag": "@0.2.0",
   "dev_compiler_rev": "@0.1.3",
   "fake_async_rev" : "@38614",
   "firefox_jsshell_rev" : "@45554",
   "glob_rev": "@704cf75e4f26b417505c5c611bdaacd8808467dd",
   "gsutil_rev" : "@33376",
   "html_tag" : "@0.12.1+1",
   "http_rev" : "@9b93e1542c753090c50b46ef1592d44bc858bfe7",
   "http_multi_server_tag" : "@1.3.2",
@@ skipping 308 matching lines @@
       '--no_resume',
       '--bucket',
       'dart-dependencies',
       '-d',
       '-r',
       Var('dart_root') + '/third_party/d8',
     ],
   },
 
 ]