## 0.12.0

* Add a `Transform.logger.fine` function that doesn't print its messages by
  default. When using Barback with pub in verbose mode, these messages will be
  printed.

* `Transformer.allowedExtensions` now supports extensions containing multiple
  periods, such as `.dart.js`.

* Transforms now pass their primary inputs through to the next phase by default.
  A transformer may still overwrite its primary input without causing a
  collision. If a transformer doesn't overwrite its primary input, it may cause
  it not to be passed through by calling `Transform.consumePrimary`. The primary
  input will be consumed by default if a transformer throws an error.

* If an input requested with `Transform.getInput`, `Transform.readInput`, or
  `Transform.readInputAsString` cannot be found, an `AssetNotFoundException`
  will be thrown. This was always what the documentation said, but previously a
  `MissingInputException` was thrown instead.

* If a transformer calls `Transform.logger.error`, the transformer will now be
  considered to have failed after it finishes running `apply()`. This means that
  its outputs will not be consumed by future transformers and its primary input
  will not be passed through to the next phase.

Add a changelog to barback.
Add a changelog to barback.

R=rnystrom@google.com
BUG=

Review URL: https://codereview.chromium.org//199133003

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@33680 260f80e4-7a28-3924-810f-c04153c831b5
