Report correct socket error and use HttpServer:close future in pub.

sdk/lib/_internal/pub/lib/src/utils.dart

Index: sdk/lib/_internal/pub/lib/src/utils.dart
diff --git a/sdk/lib/_internal/pub/lib/src/utils.dart b/sdk/lib/_internal/pub/lib/src/utils.dart
index d3ea1b609b83e320888561f90dcaeac3808142d9..988d8d0c7dfbdc039d092a52ab618bcc80f11205 100644
--- a/sdk/lib/_internal/pub/lib/src/utils.dart
+++ b/sdk/lib/_internal/pub/lib/src/utils.dart
@@ -149,13 +149,6 @@ String sha1(String source) {
   return CryptoUtils.bytesToHex(sha.close());
 }
 
-/// Returns a [Future] that completes in [milliseconds].
-Future sleep(int milliseconds) {
-  var completer = new Completer();
-  new Timer(new Duration(milliseconds: milliseconds), completer.complete);
-  return completer.future;
-}
-
 /// Configures [future] so that its result (success or exception) is passed on
 /// to [completer].
 void chainToCompleter(Future future, Completer completer) {