Now that pub is using scheduled_test, it should at least be clearer what's going
on if these tests start flaking again.

BUG=8511,8868

Review URL: https://codereview.chromium.org//12422015

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@20291 260f80e4-7a28-3924-810f-c04153c831b5