Make StreamController's unnamed constructor create a single-sub stream.

utils/pub/io.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.
 
 /// Helper functionality to make working with IO easier.
 library io;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
@@ skipping 545 matching lines @@
   var completer = new Completer<String>();
   var buffer = new StringBuffer();
   stream.onClosed = () => completer.complete(buffer.toString());
   stream.onData = () => buffer.add(stream.read());
   stream.onError = (e) => completer.completeError(e, stackTrace);
   return completer.future;
 }
 
 /// Wraps [stream] in a single-subscription [Stream] that emits the same data.
 Stream<List<int>> wrapInputStream(InputStream stream) {
-  var controller = new StreamController.singleSubscription();
-  if (stream.closed) return controller..close();
+  var controller = new StreamController();
+  if (stream.closed) {
+    controller.close();
+    return controller.stream;
+  }
 
   stream.onClosed = controller.close;
   stream.onData = () => controller.add(stream.read());
   stream.onError = (e) => controller.signalError(new AsyncError(e));
   return controller.stream;
 }
 
 // TODO(nweiz): remove this ASAP (issue 7807).
 /// Wraps [stream] in an [InputStream].
 InputStream streamToInputStream(Stream<List<int>> stream) {
@@ skipping 450 matching lines @@
 Directory _getDirectory(entry) {
   if (entry is Directory) return entry;
   return new Directory(entry);
 }
 
 /// Gets a [Uri] for [uri], which can either already be one, or be a [String].
 Uri _getUri(uri) {
   if (uri is Uri) return uri;
   return new Uri.fromString(uri);
 }