Fix some warnings in pub and pkg packages.

pkg/unittest/lib/unittest.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.
 
 /**
  * A library for writing dart unit tests.
  *
  * To import this library, install the
  * [unittest package](http://pub.dartlang.org/packages/unittest) via the pub
  * package manager. See the [Getting Started](http://pub.dartlang.org/doc)
@@ skipping 183 matching lines @@
 
 /**
  * Description text of the current test group. If multiple groups are nested,
  * this will contain all of their text concatenated.
  */
 String _currentGroup = '';
 
 /** Separator used between group names and test names. */
 String groupSep = ' ';
 
+// TODO(nweiz): present an unmodifiable view of this once issue 8321 is fixed.
 /** Tests executed in this suite. */
-final List<TestCase> _testCases = new List<TestCase>();
-
-/** Get the list of tests. */
-final List<TestCase> testCases = new UnmodifiableListView(_testCases);
+final List<TestCase> testCases = new List<TestCase>();
 
 /** Setup function called before each test in a group */
 Function _testSetup;
 
 /** Teardown function called after each test in a group */
 Function _testTeardown;
 
 int _currentTestCaseIndex = 0;
 
 /** [TestCase] currently being executed. */
@@ skipping 638 matching lines @@
 }
 
 /** Enable a test by ID. */
 void enableTest(int testId) => _setTestEnabledState(testId, true);
 
 /** Disable a test by ID. */
 void disableTest(int testId) => _setTestEnabledState(testId, false);
 
 /** Signature for a test function. */
 typedef dynamic TestFunction();