Make pkg/stack_trace use stack chains.

pkg/scheduled_test/lib/src/descriptor/directory_descriptor.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 descriptor.directory;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:path/path.dart' as path;
+import 'package:stack_trace/stack_trace.dart';
 
 import '../../descriptor.dart';
 import '../../scheduled_test.dart';
 import '../utils.dart';
 
 /// A descriptor describing a directory containing multiple files.
 class DirectoryDescriptor extends Descriptor implements LoadableDescriptor {
   /// The entries contained within this directory. This is intentionally
   /// mutable.
   final List<Descriptor> contents;
 
   DirectoryDescriptor(String name, Iterable<Descriptor> contents)
       : super(name),
         contents = contents.toList();
 
   Future create([String parent]) => schedule(() {
     if (parent == null) parent = defaultRoot;
     var fullPath = path.join(parent, name);
-    return new Directory(fullPath).create(recursive: true).then((_) {
+    return Chain.track(new Directory(fullPath).create(recursive: true))
+        .then((_) {
       return Future.wait(
           contents.map((entry) => entry.create(fullPath)).toList());
     });
   }, 'creating directory:\n${describe()}');
 
   Future validate([String parent]) => schedule(() => validateNow(parent),
       'validating directory:\n${describe()}');
 
   Future validateNow([String parent]) {
     if (parent == null) parent = defaultRoot;
     var fullPath = path.join(parent, name);
     if (!new Directory(fullPath).existsSync()) {
       fail("Directory not found: '$fullPath'.");
     }
 
     return Future.wait(contents.map((entry) {
-      return new Future.sync(() => entry.validateNow(fullPath))
+      return syncFuture(() => entry.validateNow(fullPath))
           .then((_) => null)
           .catchError((e) => e);
     })).then((results) {
       var errors = results.where((e) => e != null);
       if (errors.isEmpty) return;
       throw _DirectoryValidationError.merge(errors);
     });
   }
 
   Stream<List<int>> load(String pathToLoad) {
-    return futureStream(new Future.value().then((_) {
+    return futureStream(syncFuture(() {
       if (path.posix.isAbsolute(pathToLoad)) {
         throw new ArgumentError("Can't load absolute path '$pathToLoad'.");
       }
 
       var split = path.posix.split(path.posix.normalize(pathToLoad));
       if (split.isEmpty || split.first == '.' || split.first == '..') {
         throw new ArgumentError("Can't load '$pathToLoad' from within "
             "'$name'.");
       }
 
@@ skipping 56 matching lines @@
 
   _DirectoryValidationError(Iterable errors)
       : errors = errors.map((e) => e.toString()).toList();
 
   String toString() {
     if (errors.length == 1) return errors.single;
     return errors.map((e) => prefixLines(e, prefix: '  ', firstPrefix: '* '))
         .join('\n');
   }
 }