Roll Observatory packages and add a roll script

path/lib/src/style/url.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 path.style.url;
-
-import '../characters.dart' as chars;
-import '../internal_style.dart';
-
-/// The style for URL paths.
-class UrlStyle extends InternalStyle {
-  UrlStyle();
-
-  final name = 'url';
-  final separator = '/';
-  final separators = const ['/'];
-
-  // Deprecated properties.
-
-  final separatorPattern = new RegExp(r'/');
-  final needsSeparatorPattern =
-      new RegExp(r"(^[a-zA-Z][-+.a-zA-Z\d]*://|[^/])$");
-  final rootPattern = new RegExp(r"[a-zA-Z][-+.a-zA-Z\d]*://[^/]*");
-  final relativeRootPattern = new RegExp(r"^/");
-
-  bool containsSeparator(String path) => path.contains('/');
-
-  bool isSeparator(int codeUnit) => codeUnit == chars.SLASH;
-
-  bool needsSeparator(String path) {
-    if (path.isEmpty) return false;
-
-    // A URL that doesn't end in "/" always needs a separator.
-    if (!isSeparator(path.codeUnitAt(path.length - 1))) return true;
-
-    // A URI that's just "scheme://" needs an extra separator, despite ending
-    // with "/".
-    return path.endsWith("://") && rootLength(path) == path.length;
-  }
-
-  int rootLength(String path) {
-    if (path.isEmpty) return 0;
-    if (isSeparator(path.codeUnitAt(0))) return 1;
-    var index = path.indexOf("/");
-    if (index > 0 && path.startsWith('://', index - 1)) {
-      // The root part is up until the next '/', or the full path. Skip
-      // '://' and search for '/' after that.
-      index = path.indexOf('/', index + 2);
-      if (index > 0) return index;
-      return path.length;
-    }
-    return 0;
-  }
-
-  bool isRootRelative(String path) =>
-      path.isNotEmpty && isSeparator(path.codeUnitAt(0));
-
-  String getRelativeRoot(String path) => isRootRelative(path) ? '/' : null;
-
-  String pathFromUri(Uri uri) => uri.toString();
-
-  Uri relativePathToUri(String path) => Uri.parse(path);
-  Uri absolutePathToUri(String path) => Uri.parse(path);
-}