Use stream matchers to unflake the mac OS watcher tests.

R=rnystrom@google.com
BUG=15024

Review URL: https://codereview.chromium.org//129473003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/watcher@31705 260f80e4-7a28-3924-810f-c04153c831b5
6 files changed
tree: 5aacd0e2f91bfbadc5bbb873059378405472825f
  1. pkgs/