Delete old tests that aren't used and/or useful any more.

tests/_chrome/sample_test.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.
-
-library sample_test;
-
-import 'package:unittest/unittest.dart';
-import 'package:unittest/html_config.dart';
-import 'dart:_chrome' as _chrome;
-
-main() {
-  useHtmlConfiguration();
-  test('access', () {
-    var window = _chrome.app.window;
-    expect(window is _chrome.WindowModule, true);
-  });
-
-  test('fails from browser', () {
-    // APIs should not work in standard browser apps.
-    expect(() {
-      _chrome.app.window.create('IntentionallyMissingFile.html');
-    }, throws);
-  });
-}