Move unittest from lib to pkg.

tests/lib/unittest/mock_test.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.
 
 #library('unittestTest');
-#import('../../../lib/unittest/unittest.dart');
+#import('../../../pkg/unittest/unittest.dart');
 
 class MockList extends Mock implements List {
 }
 
 class Foo {
   sum(a, b, c) => a + b + c;
 }
 
 class FooSpy extends Mock implements Foo {
   Foo real;
@@ skipping 610 matching lines @@
     expect(log.logs, hasLength(6));
     expect(log.logs.every((e) => e.mockName == 'm2' || e.mockName == 'm3'),
         isTrue);
     m2.clearLogs();
     expect(log.logs, hasLength(3));
     expect(log.logs.every((e) => e.mockName =='m3'), isTrue);
     m3.clearLogs();
     expect(log.logs, hasLength(0));
   });
 }