Roll Observatory packages and add a roll script

analyzer/lib/instrumentation/file_instrumentation.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 file_instrumentation;
-
-import 'dart:io';
-
-import 'package:analyzer/instrumentation/instrumentation.dart';
-
-/**
- * An [InstrumentationServer] that writes to a file.
- */
-class FileInstrumentationServer implements InstrumentationServer {
-  IOSink _sink;
-
-  FileInstrumentationServer(String path) {
-    File file = new File(path);
-    _sink = file.openWrite();
-  }
-
-  @override
-  void log(String message) {
-    _sink.writeln(message);
-  }
-
-  @override
-  void logWithPriority(String message) {
-    log(message);
-  }
-
-  @override
-  void shutdown() {
-    _sink.close();
-    _sink = null;
-  }
-}