Move unittest from lib to pkg.

lib/unittest/html_config.dart

-// Copyright (c) 2011, 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 simple unit test library for running tests in a browser.
- */
-#library('unittest');
-
-#import('dart:html');
-#import('unittest.dart');
-
-#source('html_print.dart');
-
-class HtmlConfiguration extends Configuration {
-  /** Whether this is run within dartium layout tests. */
-  final bool _isLayoutTest;
-  HtmlConfiguration(this._isLayoutTest);
-
-  // TODO(rnystrom): Get rid of this if we get canonical closures for methods.
-  EventListener _onErrorClosure;
-
-  void onInit() {
-    _onErrorClosure =
-        (e) => handleExternalError(e, '(DOM callback has errors)');
-  }
-
-  void onStart() {
-    window.postMessage('unittest-suite-wait-for-done', '*');
-    // Listen for uncaught errors.
-    window.on.error.add(_onErrorClosure);
-  }
-
-  void onTestResult(TestCase testCase) {}
-
-  void onDone(int passed, int failed, int errors, List<TestCase> results,
-      String uncaughtError) {
-    window.on.error.remove(_onErrorClosure);
-    _showResultsInPage(passed, failed, errors, results, _isLayoutTest,
-        uncaughtError);
-    window.postMessage('unittest-suite-done', '*');
-  }
-}
-
-void useHtmlConfiguration([bool isLayoutTest = false]) {
-  configure(new HtmlConfiguration(isLayoutTest));
-}