Make observable transform a barback transform.

pkg/codegen/lib/codegen.dart

Index: pkg/codegen/lib/codegen.dart
diff --git a/tests/language/reexport_core_helper.dart b/pkg/codegen/lib/codegen.dart
similarity index 77%
copy from tests/language/reexport_core_helper.dart
copy to pkg/codegen/lib/codegen.dart
index 49798aa483b6602490991fcd368dda37d9566f20..f9feb8fc71c68bb448e02d68479852ab031f9231 100644
--- a/tests/language/reexport_core_helper.dart
+++ b/pkg/codegen/lib/codegen.dart
@@ -2,7 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library reexport_core_helper;
-
-export 'dart:core';
+library codegen;

[Jennifer Messerly, 2013/08/09 05:44:03]

IMHO -- this is way too generic of a name given the current content of this
package.

Since there isn't much here, could we merge this into another pkg?
Could they plausibly be helpers inside source_maps? Or analyzer, since it's
concerned with analysis and code transformation (refactorings etc)?

[Siggi Cherem (dart-lang), 2013/08/09 22:09:09]

Ok - refactored things a bit.
These two helpers moved to source_maps. but code-printer is now more generic (no
'Declarations'). I moved the tests there too and added a couple tests for
NestedPrinter.

We might want to rename 'source_maps' though. Ideas welcomed :-)

 
+export 'printer.dart';
+export 'refactor.dart';