Switch transformers over to source_span

pkg/polymer/pubspec.yaml

Index: pkg/polymer/pubspec.yaml
diff --git a/pkg/polymer/pubspec.yaml b/pkg/polymer/pubspec.yaml
index 6b35dc86589dff1e6280625bfdefca5aefc22580..a50d1f34aeac2316db0c6ed2d4fa260cf703460c 100644
--- a/pkg/polymer/pubspec.yaml
+++ b/pkg/polymer/pubspec.yaml
@@ -9,16 +9,17 @@ homepage: https://www.dartlang.org/polymer-dart/
 dependencies:
   analyzer: '>=0.15.6 <0.16.0'
   args: '>=0.10.0 <0.13.0'
-  barback: '>=0.9.0 <0.15.0'
+  barback: '>=0.14.2 <0.15.0'
   browser: '>=0.10.0 <0.11.0'
-  code_transformers: '>=0.1.4 <0.2.0'
-  html5lib: '>=0.11.0 <0.12.0'
+  code_transformers: '>=0.2.0 <0.3.0'
+  html5lib: '>=0.11.0 <0.13.0'
   logging: '>=0.9.0 <0.10.0'
   observe: '>=0.12.0-dev <0.13.0'
   path: '>=0.9.0 <2.0.0'
   polymer_expressions: '>=0.12.0-dev <0.13.0'
   smoke: '>=0.2.0-dev <0.3.0'
   source_maps: '>=0.9.0 <0.10.0'
+  source_span: '>=1.0.0 <2.0.0'
   template_binding: '>=0.12.0-dev <0.13.0'
   web_components: '>=0.5.0-dev <0.6.0'
   yaml: '>=0.9.0 <3.0.0'