Fix apidoc generation of pkg on Windows

utils/apidoc/apidoc.dart

 // Copyright (c) 2012, 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.
 
 /**
  * This generates the reference documentation for the core libraries that come
  * with dart. It is built on top of dartdoc, which is a general-purpose library
  * for generating docs from any Dart code. This library extends that to include
  * additional information and styling specific to our standard library.
  *
@@ skipping 94 matching lines @@
   // Add all of the core libraries.
   final apidocLibraries = <Path>[];
   DART2JS_LIBRARY_MAP.forEach((String name, LibraryInfo info) {
     if (!info.isInternal) {
       apidocLibraries.add(new Path('dart:$name'));
     }
   });
 
   final includedLibraries = <String>[];
   var lister = new Directory.fromPath(
-      doc.scriptDir.append('../../pkg/')).list();
+      doc.scriptDir.append('../../pkg')).list();
   lister.onDir = (dirPath) {
-    var path = new Path(dirPath);
+    var path = new Path.fromNative(dirPath);
     var libname = path.filename;
     path = path.append('${libname}.dart');
     if (new File.fromPath(path).existsSync()) {
       apidocLibraries.add(path);
       includedLibraries.add(libname);
     } else {
       print('Warning: could not find package at $path');
     }
   };
   lister.onDone = (success) {
@@ skipping 398 matching lines @@
     final typeName = member.surroundingDeclaration.simpleName;
     var memberName = '$typeName.${member.simpleName}';
     if (member is MethodMirror && (member.isConstructor || member.isFactory)) {
       final separator = member.constructorName == '' ? '' : '.';
       memberName = 'new $typeName$separator${member.constructorName}';
     }
 
     return a(memberUrl(member), memberName);
   }
 }