Roll Observatory packages and add a roll script

packages/code_transformers/CHANGELOG.md

+## 0.2.9+4
+
+* Republish 0.2.9+2 under new version.
+
+## 0.2.9+3
+
+* Republish of 0.2.9 to ensure nobody gets 0.2.9+1 in the future.
+
+## 0.2.9+2
+
+* Update to analyzer '>=0.26.0 <0.27.0'
+
+## 0.2.9+1
+
+* Update to analyzer '<0.27.0'
+* This version will be reverted as it wasn't compatible with <0.26.0.
+
+## 0.2.9
+
+* Update to analyzer `<=0.26.0`.
+
+## 0.2.8
+
+* Add `benchmarks.dart` file which exposes a `TransformerBenchmark`. This can be
+used to implement simple benchmarks of transformer code.
+
+## 0.2.7+2
+
+* Fix `assetIdToUri` on windows,
+[41](https://github.com/dart-lang/polymer-dart/issues/41)
+
+## 0.2.7+1
+
+* Fixes for missing overrides after upgrade to analzyer 0.24.0
+
+## 0.2.7
+
+* Added default set of mockSdkSources and upgraded to analyzer 0.24.0
+
+## 0.2.6
+
+* Added `assetIdToUri` to assets.dart.
+
+## 0.2.5
+* Improvements to `dartSdkDirectory` so it has a better chance of success.
+* `BuildLogger` now accepts `AggregateTransform` or `Transform`. If passing in
+an `AggregateTransform` you must also pass in an `AssetId` to use as the primary
+input.
+
+## 0.2.4
+
+* Added some basic string formatting options to `testPhases` to make it a bit
+  less strict if desired.
+
+## 0.2.3+2
+
+* Added logic to discover the location of the dart SDK when the dart binary is a
+  symlink.
+
+## 0.2.3
+
+* Added support for logging stable error messages from transformers.
+
+## 0.2.2
+
+* Added two transformers, 'delete_file' and 'remove_sourcemap_comment'.
+
+## 0.2.0+3
+
+* Raise the lower bound on the source_maps constraint to exclude incompatible
+  versions.
+
+## 0.2.0+2
+
+* Widen the constraint on source_maps.
+
+## 0.2.0+1
+
+* Widen the constraint on barback.
+
+## 0.2.0
+
+* Switch from `source_maps`' `Span` class to `source_span`'s `SourceSpan` class.