Update the co19 dep to point to the GitHub repo.

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
   "third_party": "http://dart.googlecode.com/svn/third_party",
 
   # The svn location for pulling pinned revisions of bleeding edge dependencies.
   "bleeding_edge": "http://dart.googlecode.com/svn/branches/bleeding_edge",
 
   # Use this googlecode_url variable only if there is an internal mirror for it.
   # If you do not know, use the full path while defining your new deps entry.
   "googlecode_url": "http://%s.googlecode.com/svn",
 
   "gyp_rev": "@1752",
-  "co19_rev": "@801",
+  "co19_rev": "@20c5a7306a7bcee037cc3988a84e5486c6e1a78e",
   "chromium_url": "http://src.chromium.org/svn",
   "chromium_git": "https://chromium.googlesource.com",
 
   # Revisions of /third_party/* dependencies.
   "7zip_rev" : "@19997",
   "analyzer_cli_tag" : "@1.0.1",
   "args_tag": "@0.13.0",
   "barback_rev" : "@29ee90dbcf77cfd64632fa2797a4c8a4f29a4b51",
   "chrome_rev" : "@19997",
   "clang_rev" : "@28450",
@@ skipping 60 matching lines @@
   "barback-0.14.0_rev": "@36398",
   "barback-0.14.1_rev": "@38525",
   "source_maps-0.9.4_rev": "@38524",
 }
 
 deps = {
   # Stuff needed for GYP to run.
   Var("dart_root") + "/third_party/gyp":
       (Var("googlecode_url") % "gyp") + "/trunk" + Var("gyp_rev"),
 
-  Var("dart_root") + "/tests/co19/src": ((Var("googlecode_url") % "co19") +
-      "/trunk/co19/tests/co19/src" + Var("co19_rev")),
+  Var("dart_root") + "/tests/co19/src":
+      "https://github.com/dart-lang/co19.git" + Var("co19_rev"),
 
   Var("dart_root") + "/third_party/nss":
       Var("chromium_git") + "/chromium/deps/nss.git" + Var("nss_rev"),
 
   Var("dart_root") + "/third_party/sqlite":
       Var("chromium_git") + "/chromium/src/third_party/sqlite.git" +
       Var("sqlite_rev"),
 
   Var("dart_root") + "/third_party/zlib":
       Var("chromium_git") + "/chromium/src/third_party/zlib.git" +
@@ skipping 190 matching lines @@
       '--no_auth',
       '--no_resume',
       '--bucket',
       'dart-dependencies',
       '-d',
       '-r',
       Var('dart_root') + '/tools/testing/bin',
     ],
   },
 ]