Step one towards stable error messages with details:
 - switches polymer to use a messages type
 - autogenerates an HTML page from the message list.
 - use these messages on polymer transformers
 - moves build_logger to code_Transformers, so we can also use this in other packages.

Still pending to do more, for example, find a permanent location and URI scheme for messages
so we can show them on the command-line, improve the UI to tak advantage of clustering, etc.

But I think it's good enough to get it in and iterate afterwards

R=jakemac@google.com, kathyw@google.com

Review URL: https://codereview.chromium.org//513023002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/observe@39884 260f80e4-7a28-3924-810f-c04153c831b5
6 files changed
tree: d873795a3a48b1b5ab181e7df4d4af0b9aade974
  1. lib/
  2. test/
  3. AUTHORS
  4. CHANGELOG.md
  5. LICENSE
  6. PATENTS
  7. pubspec.yaml