Roll Observatory packages and add a roll script

packages/polymer_expressions/benchmark/all.dart

 // Copyright (c) 2013, 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 args;
+library polymer_expressions.benchmark.all;
 
-export 'src/arg_parser.dart';
-export 'src/arg_results.dart' hide newArgResults;
-export 'src/option.dart' hide newOption;
+import 'parse.dart' as parse;
+import 'eval.dart' as eval;
+
+main() {
+  parse.main();
+  eval.main();
+}