Update test and scheduled_test in DEPS

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",
 
   # We use mirrors of all github repos to guarantee reproducibility and
@@ skipping 74 matching lines @@
   "plugin_tag": "@0.2.0",
   "ply_rev": "@604b32590ffad5cbb82e4afef1d305512d06ae93",
   "pool_tag": "@1.2.1",
   "protobuf_tag": "@0.5.1+1",
   "pub_cache_tag": "@v0.1.0",
   "pub_rev": "@488ab539770512a234f0a01b74882dcbb3f1a4da",
   "pub_semver_tag": "@1.2.1",
   "quiver_tag": "@0.21.4",
   "resource_rev":"@a49101ba2deb29c728acba6fb86000a8f730f4b1",
   "root_certificates_rev": "@aed07942ce98507d2be28cbd29e879525410c7fc",
-  "scheduled_test_tag": "@0.12.5+6",
+  "scheduled_test_tag": "@0.12.6",
   "shelf_static_tag": "@0.2.3+4",
   "shelf_tag": "@0.6.5+2",
   "shelf_web_socket_tag": "@0.2.0",
   "smoke_rev" : "@f3361191cc2a85ebc1e4d4c33aec672d7915aba9",
   "source_map_stack_trace_tag": "@1.0.4",
   "source_maps-0.9.4_rev": "@38524",
   "source_maps_tag": "@0.10.1",
   "source_span_tag": "@1.2.0",
   "stack_trace_tag": "@1.4.2",
   "stream_channel_tag": "@1.3.1",
   "string_scanner_tag": "@0.1.4",
   "sunflower_rev": "@879b704933413414679396b129f5dfa96f7a0b1e",
   "test_reflective_loader_tag": "@0.0.3",
-  "test_tag": "@0.12.13+5",
+  "test_tag": "@0.12.15+1",
   "typed_data_tag": "@1.1.2",
   "usage_rev": "@b5080dac0d26a5609b266f8fdb0d053bc4c1c638",
   "utf_rev": "@1f55027068759e2d52f2c12de6a57cce5f3c5ee6",
   "watcher_tag": "@0.9.7+2",
   "web_components_rev": "@6349e09f9118dce7ae1b309af5763745e25a9d61",
   "web_socket_channel_tag": "@1.0.4",
   "WebCore_rev": "@a86fe28efadcfc781f836037a80f27e22a5dad17",
   "when_tag": "@0.2.0+2",
   "which_tag": "@0.1.3+1",
   "yaml_tag": "@2.1.5",
@@ skipping 354 matching lines @@
       "--extract",
       "-s",
       Var('dart_root') + "/third_party/clang.tar.gz.sha1",
     ],
   },
   {
     "pattern": ".",
     "action": ["python", Var("dart_root") + "/tools/gyp_dart.py"],
   },
 ]