Roll Observatory packages and add a roll script

packages/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.
 
 /**
  */
 library logging;
 
 import 'dart:async';
 import 'dart:collection';
@@ skipping 43 matching lines @@
   StreamController<LogRecord> _controller;
 
   /**
    * Singleton constructor. Calling `new Logger(name)` will return the same
    * actual instance whenever it is called with the same string name.
    */
   factory Logger(String name) {
     return _loggers.putIfAbsent(name, () => new Logger._named(name));
   }
 
+  /// Creates a new detached [Logger].
+  ///
+  /// Returns a new [Logger] instance (unlike `new Logger`, which returns a
+  /// [Logger] singleton), which doesn't have any parent or children,
+  /// and it's not a part of the global hierarchial loggers structure.
+  ///
+  /// It can be useful when you just need a local short-living logger,
+  /// which you'd like to be garbage-collected later.
+  factory Logger.detached(String name) {
+    return new Logger._internal(name, null, new Map<String, Logger>());
+  }
+
   factory Logger._named(String name) {
     if (name.startsWith('.')) {
       throw new ArgumentError("name shouldn't start with a '.'");
     }
     // Split hierarchical names (separated with '.').
     int dot = name.lastIndexOf('.');
     Logger parent = null;
     String thisName;
     if (dot == -1) {
       if (name != '') parent = new Logger('');
@@ skipping 269 matching lines @@
   /** Zone of the calling code which resulted in this LogRecord. */
   final Zone zone;
 
   LogRecord(this.level, this.message, this.loggerName,
       [this.error, this.stackTrace, this.zone])
       : time = new DateTime.now(),
         sequenceNumber = LogRecord._nextNumber++;
 
   String toString() => '[${level.name}] $loggerName: $message';
 }