pkg/logging: removed deprecated 'on' API

Review URL: https://codereview.chromium.org//12600033

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/logging@20574 260f80e4-7a28-3924-810f-c04153c831b5
3 files changed
tree: 1b3093866fb1094cc511e1a579584159f0b6fb2b
  1. lib/
  2. test/
  3. pubspec.yaml