Update to latest version of watcher.

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 = {
   # 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",
@@ skipping 59 matching lines @@
   "smoke_rev" : "@f3361191cc2a85ebc1e4d4c33aec672d7915aba9",
   "snakeyaml_rev" : "@19997",
   "source_maps_rev": "@379b4f31c4e2987eb15934d1ad8b419c6cc897b3",
   "sqlite_rev": "@38811b79f42801662adc0458a25270ab690a6b81",
   "shelf_web_socket_rev": "@ff170cec2c0e4e5722cdf47c557be63b5035a602",
   "source_span_rev": "@42501132e43599a151ba6727d340e44442f86c05",
   "stack_trace_rev": "@62a0cfe0c3e7270b75d71a7f356599bb63e5ae4e",
   "string_scanner_rev": "@3e7617d6f74ba382e9b6130b1cc12091d89a9bc5",
   "sunflower_rev": "@879b704933413414679396b129f5dfa96f7a0b1e",
   "unittest_rev": "@1625274a8b6309588eb4c0017b5b672a96ad3230",
-  "watcher_rev": "@f1015e987b4e5a3b7fb65d8716ae9b5ee372b470",
+  "watcher_tag": "@0.9.4",
   "web_components_rev": "@0e636b534d9b12c9e96f841e6679398e91a986ec",
   "websocket_rev" : "@35854",
   "WebCore_rev" : "@40446",
   "weberknecht_rev" : "@33599",
   "yaml_rev": "@563a5ffd4a800a2897b8f4dd6b19f2a370df2f2b",
   "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",
@@ skipping 144 matching lines @@
       "https://github.com/dart-lang/stack_trace.git" + Var("stack_trace_rev"),
   "dart/third_party/pkg/string_scanner":
       "https://github.com/dart-lang/string_scanner.git" +
       Var("string_scanner_rev"),
   "dart/third_party/sunflower":
       "https://github.com/dart-lang/sample-sunflower.git" +
       Var("sunflower_rev"),
   "dart/third_party/pkg/unittest":
       "https://github.com/dart-lang/unittest.git" + Var("unittest_rev"),
   "dart/third_party/pkg/watcher":
-      "https://github.com/dart-lang/watcher.git" + Var("watcher_rev"),
+      "https://github.com/dart-lang/watcher.git" + Var("watcher_tag"),
   "dart/third_party/pkg/web_components":
       "https://github.com/dart-lang/web-components.git" +
       Var("web_components_rev"),
   "dart/third_party/pkg/yaml":
       "https://github.com/dart-lang/yaml.git" + Var("yaml_rev"),
 
   # These specific versions of barback and source_maps are used for testing and
   # should be pulled from bleeding_edge even on channels.
   "dart/third_party/pkg/barback-0.13.0":
       "/branches/bleeding_edge/dart/pkg/barback" + Var("barback-0.13.0_rev"),
@@ skipping 34 matching lines @@
   },
   {
     "pattern": ".",
     "action": ["python", "dart/editor/build/generate_sources.py"],
   },
   {
     "pattern": ".",
     "action": ["python", "dart/tools/gyp_dart.py"],
   },
 ]