Move unittest from lib to pkg.

tests/html/window_nosuchmethod_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('WindowNSMETest');
-#import('../../lib/unittest/unittest.dart');
-#import('../../lib/unittest/html_config.dart');
+#import('../../pkg/unittest/unittest.dart');
+#import('../../pkg/unittest/html_config.dart');
 #import('dart:html', prefix: 'dom');
 
 // Not defined in dom.Window.
 foo(x) => x;
 
 class Unused {
   foo(x) => 'not $x';
 }
 
 int inscrutable(int x) => x == 0 ? 0 : x | inscrutable(x & (x - 1));
@@ skipping 27 matching lines @@
       try {
         String x = dom.window.foo(message);
         Expect.fail('Should not reach here: $x');
       } catch (NoSuchMethodException e) {
         // Expected exception.
       } catch (Exception e) {
         Expect.fail('Wrong exception: $e');
       }
     }); 
 }