Use filtered stacks in pub, barback, and watcher tests.

This also exposes more unittest stuff to users of scheduled_test.

R=rnystrom@google.com
BUG=

Review URL: https://codereview.chromium.org//23582003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/watcher@26751 260f80e4-7a28-3924-810f-c04153c831b5
diff --git a/pkgs/watcher/test/utils.dart b/pkgs/watcher/test/utils.dart
index 3bbe0e1..656ddf8 100644
--- a/pkgs/watcher/test/utils.dart
+++ b/pkgs/watcher/test/utils.dart
@@ -38,6 +38,7 @@
 
 void initConfig() {
   useCompactVMConfiguration();
+  filterStacks = true;
 }
 
 /// Creates the sandbox directory the other functions in this library use and