fixes #131, use before define from variables to classes

lib/src/dependency_graph.dart

Index: lib/src/dependency_graph.dart
diff --git a/lib/src/dependency_graph.dart b/lib/src/dependency_graph.dart
index 09ef37aaa5feab977bd8a8b2dfbb100ccdcb813d..dcded66942caf4a90baf757f77e1483f85cf5e30 100644
--- a/lib/src/dependency_graph.dart
+++ b/lib/src/dependency_graph.dart
@@ -475,20 +475,21 @@ const corelibOrder = const [
   'dart.collection',
   'dart._internal',
   'dart.math',
+  'dart.async',

[Jennifer Messerly, 2015/05/12 16:23:46]

stole this from your CL. Gets sunflower working

   'dart._foreign_helper',
+  'dart._js_embedded_names',
+  'dart._js_names',
   'dart._js_helper',
+  'dart.isolate',
+  'dart.typed_data',
+  'dart._isolate_helper',
+  'dart._js_primitives',
+
   // TODO(jmesserly): add others
   /*
-  'dart.async',
   'dart.convert',
-  'dart.isolate',
-  'dart.typed_data',
   'dart._foreign_helper',
   'dart._interceptors',
-  'dart._isolate_helper',
-  'dart._js_embedded_names',
-  'dart._js_names',
-  'dart._js_primitives',
   'dart._native_typed_data',
   */
 ];