Add Directory.systemTemp getter to replace createSystemTemp().

sdk/lib/_internal/pub/lib/src/io.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.
 
 /// Helper functionality to make working with IO easier.
 library pub.io;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
@@ skipping 210 matching lines @@
     if (ex.osError.errorCode == 17 || ex.osError.errorCode == 183) {
       log.fine("Got 'already exists' error when creating directory.");
     } else {
       throw ex;
     }
   }
 
   return dirPath;
 }
 
-/// Creates a temp directory whose name will be based on [dir] with a unique
-/// suffix appended to it. If [dir] is not provided, a temp directory will be
-/// created in a platform-dependent temporary location. Returns the path of the
-/// created directory.
+/// Creates a temp directory in [dir], whose name will be [prefix] with
+/// characters appended to it to make a unique name.
+/// Returns the path of the created directory.
 String createTempDir(String base, String prefix) {
   var tempDir = new Directory(base).createTempSync(prefix);
   log.io("Created temp directory ${tempDir.path}");
   return tempDir.path;
 }
 
+/// Creates a temp directory in the system temp directory, whose name will be
+/// 'pub_' with characters appended to it to make a unique name.
+/// Returns the path of the created directory.
 String createSystemTempDir() {
-  var tempDir = Directory.createSystemTempSync('pub_');
+  var tempDir = Directory.systemTemp.createTempSync('pub_');
   log.io("Created temp directory ${tempDir.path}");
   return tempDir.path;
 }
 
-
 /// Lists the contents of [dir]. If [recursive] is `true`, lists subdirectory
 /// contents (defaults to `false`). If [includeHidden] is `true`, includes files
 /// and directories beginning with `.` (defaults to `false`).
 ///
 /// The returned paths are guaranteed to begin with [dir].
 List<String> listDir(String dir, {bool recursive: false,
     bool includeHidden: false}) {
   List<String> doList(String dir, Set<String> listedDirectories) {
     var contents = <String>[];
 
@@ skipping 574 matching lines @@
   const PubProcessResult(this.stdout, this.stderr, this.exitCode);
 
   bool get success => exitCode == 0;
 }
 
 /// 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 Uri.parse(uri);
 }