Roll Observatory packages and add a roll script

packages/dart_style/lib/src/line_splitting/line_splitter.dart

 // Copyright (c) 2015, 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 dart_style.src.line_splitting.line_splitter;
 
 import '../chunk.dart';
 import '../debug.dart' as debug;
 import '../line_writer.dart';
 import '../rule/rule.dart';
@@ skipping 179 matching lines @@
       debug.log();
     }
 
     return _bestSolution.splits;
   }
 
   void enqueue(SolveState state) {
     _queue.add(state);
   }
 }