Bring in the latest yaml version.

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 92 matching lines @@
   "test_tag": "@0.12.3+8",
   "test_reflective_loader_tag": "@0.0.3",
   "utf_rev": "@1f55027068759e2d52f2c12de6a57cce5f3c5ee6",
   "unittest_tag": "@0.11.6",
   "usage_rev": "@b5080dac0d26a5609b266f8fdb0d053bc4c1c638",
   "watcher_tag": "@0.9.7",
   "when_tag": "@0.2.0+2",
   "which_tag": "@0.1.3+1",
   "web_components_rev": "@0e636b534d9b12c9e96f841e6679398e91a986ec",
   "WebCore_rev" : "@44061",
-  "yaml_rev": "@563a5ffd4a800a2897b8f4dd6b19f2a370df2f2b",
+  "yaml_tag": "@2.1.5",
   "zlib_rev": "@c3d0a6190f2f8c924a05ab6cc97b8f975bddd33f",
   "font_awesome_rev": "@31824",
   "barback-0.13.0_rev": "@34853",
   "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.
@@ skipping 174 matching lines @@
   Var("dart_root") + "/third_party/pkg/watcher":
       (Var("github_mirror") % "watcher") + Var("watcher_tag"),
   Var("dart_root") + "/third_party/pkg/web_components":
       (Var("github_mirror") % "web-components") +
       Var("web_components_rev"),
   Var("dart_root") + "/third_party/pkg/when":
       (Var("github_mirror") % "when") + Var("when_tag"),
   Var("dart_root") + "/third_party/pkg/which":
       (Var("github_mirror") % "which") + Var("which_tag"),
   Var("dart_root") + "/third_party/pkg/yaml":
-      (Var("github_mirror") % "yaml") + Var("yaml_rev"),
+      (Var("github_mirror") % "yaml") + Var("yaml_tag"),
 
   # These specific versions of barback and source_maps are used for testing and
   # should be pulled from bleeding_edge even on channels.
   Var("dart_root") + "/third_party/pkg/barback-0.13.0":
       Var("bleeding_edge") + "/dart/pkg/barback" + Var("barback-0.13.0_rev"),
   Var("dart_root") + "/third_party/pkg/barback-0.14.0+3":
       Var("bleeding_edge") + "/dart/pkg/barback" + Var("barback-0.14.0_rev"),
   Var("dart_root") + "/third_party/pkg/barback-0.14.1+4":
       Var("bleeding_edge") + "/dart/pkg/barback" + Var("barback-0.14.1_rev"),
   Var("dart_root") + "/third_party/pkg/source_maps-0.9.4":
@@ skipping 66 matching lines @@
       "--bucket",
       "dart-dependencies",
       "--recursive",
       "--auto_platform",
       "--extract",
       "--directory",
       Var('dart_root') + "/tools/sdks",
     ],
   },
 ]