Fix pub to work with new Directory.createSystemTemp.

sdk/lib/_internal/pub/test/test_pub.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.
 
 /// Test infrastructure for testing pub. Unlike typical unit tests, most pub
 /// tests are integration tests that stage some stuff on the file system, run
 /// pub, and then validate the results. This library provides an API to build
 /// tests like that.
 library test_pub;
 
@@ skipping 319 matching lines @@
     // The windows bots are very slow, so we increase the default timeout.
     if (Platform.operatingSystem == "windows") {
       currentSchedule.timeout = new Duration(seconds: 10);
     }
 
     // Ensure the SDK version is always available.
     d.dir(sdkPath, [
       d.file('version', '0.1.2.3')
     ]).create();
 
-    _sandboxDir = createTempDir();
+    _sandboxDir = createSystemTempDir();
     d.defaultRoot = sandboxDir;
     currentSchedule.onComplete.schedule(() => deleteEntry(_sandboxDir),
         'deleting the sandbox directory');
 
     // Schedule the test.
     body();
   });
 }
 
 /// Get the path to the root "pub/test" directory containing the pub
@@ skipping 485 matching lines @@
   bool matches(item, Map matchState) {
     if (item is! Pair) return false;
     return _firstMatcher.matches(item.first, matchState) &&
         _lastMatcher.matches(item.last, matchState);
   }
 
   Description describe(Description description) {
     description.addAll("(", ", ", ")", [_firstMatcher, _lastMatcher]);
   }
 }