Revert "Remove Expect from core library."

This reverts commit 19755.

Review URL: https://codereview.chromium.org//12743005

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/yaml@19756 260f80e4-7a28-3924-810f-c04153c831b5
1 file changed
tree: 16f7f3a5884e226081b69da41f46633e1ec32135
  1. pkgs/