Move unittest from lib to pkg.

tests/html/xmlelement_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('XMLElementTest');
-#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');
 
 main() {
   useHtmlConfiguration();
 
   XMLElement makeElement() => new XMLElement.xml("<xml><foo/><bar/></xml>");
 
   makeElementWithParent() {
     final parent = new XMLElement.xml(
         "<parent><before/><xml><foo/><bar/></xml><after/></parent>");
@@ skipping 549 matching lines @@
     makeElement().rect.then(
       expectAsync1(ElementRect rect) {
         expectEmptyRect(rect.client);
         expectEmptyRect(rect.offset);
         expectEmptyRect(rect.scroll);
         expectEmptyRect(rect.bounding);
         Expect.isTrue(rect.clientRects.isEmpty());
       }));
   });
 }