Combine unmodifiable_collection package into collection_helpers.

pkg/logging/lib/logging.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Support for logging.
  *
  * For information on installing and importing this library, see the
  * [logging package on pub.dartlang.org]
  * (http://pub.dartlang.org/packages/logging).
@@ skipping 33 matching lines @@
  *       log.fine('Got the result: $result');
  *       processResult(result);
  *     })
  *     .catchError((e, stackTrace) => log.severe('Oh noes!', e, stackTrace));
  *
  * See the [Logger] class for the different logging methods.
  */
 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
  * hierarchy. When false, all logging is merged in the root logger.
  */
 bool hierarchicalLoggingEnabled = false;
 
 /**
  * Level for the root-logger. This will be the level of all loggers if
  * [hierarchicalLoggingEnabled] is false.
@@ skipping 282 matching lines @@
   /** Associated stackTrace (if any) when recording errors messages. */
   final StackTrace stackTrace;
 
   LogRecord(this.level, this.message, this.loggerName, [this.error,
                                                         this.stackTrace])
       : time = new DateTime.now(),
         sequenceNumber = LogRecord._nextNumber++;
 
   String toString() => '[${level.name}] $loggerName: $message';
 }