Update charted to 0.4.8 and roll

packages/barback/pubspec.yaml

Index: packages/barback/pubspec.yaml
diff --git a/packages/barback/pubspec.yaml b/packages/barback/pubspec.yaml
index 9c05ff187c7df198a86d50c45a4fedb8e3e5d305..7d239af1ae752c062d81ee2ecea71e08bdb08a15 100644
--- a/packages/barback/pubspec.yaml
+++ b/packages/barback/pubspec.yaml
@@ -7,7 +7,7 @@ name: barback
 #
 # When the minor or patch version of this is upgraded, you *must* update that
 # version constraint in pub to stay in sync with this.
-version: 0.15.2+7
+version: 0.15.2+11
 
 author: "Dart Team <misc@dartlang.org>"
 homepage: http://github.com/dart-lang/barback
@@ -22,13 +22,14 @@ description: >
   Runs transforms asynchronously and in parallel when possible to maximize
   responsiveness.
 dependencies:
+  async: "^1.10.0"
   path: ">=0.9.0 <2.0.0"
   pool: ">=1.0.0 <2.0.0"
   source_span: ">=1.0.0 <2.0.0"
   stack_trace: ">=0.9.1 <2.0.0"
-  collection: ">=0.9.1 <2.0.0"
+  collection: "^1.5.0"
 dev_dependencies:
   scheduled_test: ">=0.9.0 <0.11.0"
   unittest: ">=0.9.0 <0.10.0"
 environment:
-  sdk: ">=1.0.1 <2.0.0"
+  sdk: ">=1.22.0 <2.0.0"