Combine unmodifiable_collection package into collection_helpers.

Avoids some duplicated code, and makes everything much simpler.

R=floitsch@google.com

Review URL: https://codereview.chromium.org//70073003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/logging@30402 260f80e4-7a28-3924-810f-c04153c831b5
diff --git a/lib/logging.dart b/lib/logging.dart
index 25213bb..37ac67d 100644
--- a/lib/logging.dart
+++ b/lib/logging.dart
@@ -51,7 +51,7 @@
 library logging;
 
 import 'dart:async';
-import 'package:unmodifiable_collection/unmodifiable_collection.dart';
+import 'package:collection_helpers/wrappers.dart';
 
 /**
  * Whether to allow fine-grain logging and configuration of loggers in a
diff --git a/pubspec.yaml b/pubspec.yaml
index 7893523..d298608 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -5,7 +5,7 @@
 homepage: http://www.dartlang.org
 documentation: http://api.dartlang.org/docs/pkg/logging
 dependencies:
-  unmodifiable_collection: ">=0.9.0 <0.10.0"
+  collection_helpers: ">=0.9.0 <0.10.0"
 dev_dependencies:
   unittest: ">=0.9.0 <0.10.0"
 environment: