Update charted to 0.4.8 and roll

packages/path/lib/src/style/posix.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.posix;
-
 import '../characters.dart' as chars;
 import '../parsed_path.dart';
 import '../internal_style.dart';
 
 /// The style for POSIX paths.
 class PosixStyle extends InternalStyle {
   PosixStyle();
 
   final name = 'posix';
   final separator = '/';
   final separators = const ['/'];
 
   // Deprecated properties.
 
   final separatorPattern = new RegExp(r'/');
   final needsSeparatorPattern = new RegExp(r'[^/]$');
   final rootPattern = new RegExp(r'^/');
   final relativeRootPattern = null;
 
   bool containsSeparator(String path) => path.contains('/');
 
   bool isSeparator(int codeUnit) => codeUnit == chars.SLASH;
 
   bool needsSeparator(String path) =>
       path.isNotEmpty && !isSeparator(path.codeUnitAt(path.length - 1));
 
-  int rootLength(String path) {
+  int rootLength(String path, {bool withDrive: false}) {
     if (path.isNotEmpty && isSeparator(path.codeUnitAt(0))) return 1;
     return 0;
   }
 
   bool isRootRelative(String path) => false;
 
   String getRelativeRoot(String path) => null;
 
   String pathFromUri(Uri uri) {
     if (uri.scheme == '' || uri.scheme == 'file') {
@@ skipping 11 matching lines @@
       parsed.parts.addAll(["", ""]);
     } else if (parsed.hasTrailingSeparator) {
       // If the path has a trailing slash, add a single empty component so the
       // URI has a trailing slash as well.
       parsed.parts.add("");
     }
 
     return new Uri(scheme: 'file', pathSegments: parsed.parts);
   }
 }