Widen the barback constraints for code_transformers and smoke.

pkg/smoke/pubspec.yaml

 name: smoke
 version: 0.1.0-pre.2.dev
 author: Polymer.dart Authors <web-ui-dev@dartlang.org>
 homepage: "https://api.dartlang.org/apidocs/channels/be/#smoke"
 description: >
   A restricted reflective system that uses mirrors at development time, but that
   can be replaced with non-reflective calls using code generation. See README.md
   for mode details.
 dependencies:
-  barback: ">=0.9.0 <0.12.0"
+  barback: ">=0.9.0 <0.13.0"
   logging: ">=0.9.0 <0.10.0"
 # TODO(sigmund): uncomment this once we have some easier way to do global
 # app-level transformers or a way to enable this selectively from the
 # application package.
 #transformers:
 #- smoke/src/default_transformer:
 #    # TODO(sigmund): include this once this feature is available in the stable
 #    # channel, or when we really need some other feature in the dev channel.
 #    $include: lib/src/implementation.dart
 dev_dependencies:
   unittest: ">=0.10.0 <0.11.0"
   path: ">=1.0.0 <2.0.0"
 environment:
   sdk: ">=1.2.0 <2.0.0"