Add support for --pub-serve.

pubspec.yaml

Index: pubspec.yaml
diff --git a/pubspec.yaml b/pubspec.yaml
index 577cd58d9e151fa6f76e27b998dc08ab1a640328..8f012b0faff4c0b22148e2e03b5f3133990eb602 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: test
-version: 0.12.0-beta.4
+version: 0.12.0-dev
 author: Dart Team <misc@dartlang.org>
 description: A library for writing dart unit tests.
 homepage: https://github.com/dart-lang/test
@@ -8,14 +8,17 @@ environment:
 dependencies:
   analyzer: '>=0.23.0 <0.25.0'
   args: '>=0.12.1 <0.14.0'
+  barback: '>=0.14.0 <0.16.0'
   http_parser: '^0.0.2'
   pool: '^1.0.0'
+  pub_semver: '^1.0.0'
   shelf: '>=0.5.3 <0.7.0'
   shelf_static: '^0.2.0'
   shelf_web_socket: '^0.0.1'
   source_span: '^1.0.0'
   stack_trace: '^1.2.0'
   string_scanner: '^0.1.1'
+  yaml: '>=0.9.0 <3.0.0'
 
   # Use a tight version constraint to ensure that a constraint on matcher
   # properly constraints all features it provides.