Big merge from experimental to bleeding edge.

utils/pub/lock_file.dart

Index: utils/pub/lock_file.dart
diff --git a/utils/pub/lock_file.dart b/utils/pub/lock_file.dart
index 80036b845993a47f22e1e414f518d0a99f8f73c9..1e975852ff282f9e72758f4e689e9d1780fbdbc3 100644
--- a/utils/pub/lock_file.dart
+++ b/utils/pub/lock_file.dart
@@ -4,7 +4,7 @@
 
 library lock_file;
 
-import 'dart:json';
+import 'dart:json' as json;
 import 'package.dart';
 import 'source_registry.dart';
 import 'utils.dart';
@@ -85,6 +85,6 @@ class LockFile {
 
     // TODO(nweiz): Serialize using the YAML library once it supports
     // serialization. For now, we use JSON, since it's a subset of YAML anyway.
-    return JSON.stringify({'packages': packagesObj});
+    return json.stringify({'packages': packagesObj});
   }
 }