Roll Observatory packages and add a roll script

path/lib/src/utils.dart

-// Copyright (c) 2014, 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 path.utils;
-
-import 'characters.dart' as chars;
-
-/// Returns whether [char] is the code for an ASCII letter (uppercase or
-/// lowercase).
-bool isAlphabetic(int char) =>
-    (char >= chars.UPPER_A && char <= chars.UPPER_Z) ||
-        (char >= chars.LOWER_A && char <= chars.LOWER_Z);
-
-/// Returns whether [char] is the code for an ASCII digit.
-bool isNumeric(int char) => char >= chars.ZERO && char <= chars.NINE;