Update charted to 0.4.8 and roll

packages/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';
+import '../utils.dart';
 
 /// The style for URL paths.
 class UrlStyle extends InternalStyle {
   UrlStyle();
 
   final name = 'url';
   final separator = '/';
   final separators = const ['/'];
 
   // Deprecated properties.
@@ skipping 12 matching lines @@
     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) {
+  int rootLength(String path, {bool withDrive: false}) {
     if (path.isEmpty) return 0;
     if (isSeparator(path.codeUnitAt(0))) return 1;
+
+    for (var i = 0; i < path.length; i++) {
+      var codeUnit = path.codeUnitAt(i);
+      if (isSeparator(codeUnit)) return 0;
+      if (codeUnit == chars.COLON) {
+        if (i == 0) return 0;
+
+        // The root part is up until the next '/', or the full path. Skip ':'
+        // (and '//' if it exists) and search for '/' after that.
+        if (path.startsWith('//', i + 1)) i += 3;
+        var index = path.indexOf('/', i);
+        if (index <= 0) return path.length;
+
+        // file: URLs sometimes consider Windows drive letters part of the root.
+        // See https://url.spec.whatwg.org/#file-slash-state.
+        if (!withDrive || path.length < index + 3) return index;
+        if (!path.startsWith('file://')) return index;
+        if (!isDriveLetter(path, index + 1)) return index;
+        return path.length == index + 3 ? index + 3 : index + 4;
+      }
+    }
+
     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);
 }