Move some core classes to collection library.

utils/tests/pub/test_pub.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.
 
 /// 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;
 
 import 'dart:async';
+import 'dart:collection' show Queue;
 import 'dart:io';
 import 'dart:json' as json;
 import 'dart:math';
 import 'dart:uri';
 
 import '../../../pkg/oauth2/lib/oauth2.dart' as oauth2;
 import '../../../pkg/path/lib/path.dart' as path;
 import '../../../pkg/unittest/lib/unittest.dart';
 import '../../../pkg/http/lib/testing.dart';
 import '../../lib/file_system.dart' as fs;
@@ skipping 1517 matching lines @@
 /// calling [completion] is unnecessary.
 void expectLater(Future actual, matcher, {String reason,
     FailureHandler failureHandler, bool verbose: false}) {
   _schedule((_) {
     return actual.then((value) {
       expect(value, matcher, reason: reason, failureHandler: failureHandler,
           verbose: false);
     });
   });
 }