Removed Dead Code

runtime/observatory/observatory_sources.gypi

 # Copyright (c) 2015, 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.
 
 # This file contains all dart, css, and html sources for Observatory.
 {
   'sources': [
     'lib/app.dart',
     'lib/cli.dart',
     'lib/cpu_profile.dart',
@@ skipping 150 matching lines @@
     'lib/src/elements/script_inset.html',
     'lib/src/elements/script_ref.dart',
     'lib/src/elements/script_ref.html',
     'lib/src/elements/script_view.dart',
     'lib/src/elements/script_view.html',
     'lib/src/elements/service_ref.dart',
     'lib/src/elements/service_ref.html',
     'lib/src/elements/service_view.dart',
     'lib/src/elements/service_view.html',
     'lib/src/elements/shims/binding.dart',
-    'lib/src/elements/sliding_checkbox.dart',
-    'lib/src/elements/sliding_checkbox.html',
     'lib/src/elements/timeline_page.dart',
     'lib/src/elements/timeline_page.html',
     'lib/src/elements/view_footer.dart',
     'lib/src/elements/vm_connect_target.dart',
     'lib/src/elements/vm_connect_target_wrapper.dart',
     'lib/src/elements/vm_connect.dart',
     'lib/src/elements/vm_connect.html',
-    'lib/src/elements/vm_ref.dart',
-    'lib/src/elements/vm_ref.html',
     'lib/src/elements/vm_view.dart',
     'lib/src/elements/vm_view.html',
     'lib/src/mocks/exceptions/connection_exception.dart',
     'lib/src/mocks/objects/error.dart',
     'lib/src/mocks/objects/event.dart',
     'lib/src/mocks/objects/class.dart',
     'lib/src/mocks/objects/isolate.dart',
     'lib/src/mocks/objects/library.dart',
     'lib/src/mocks/objects/notification.dart',
     'lib/src/mocks/objects/script.dart',
@@ skipping 25 matching lines @@
     'lib/utils.dart',
     'web/favicon.ico',
     'web/index.html',
     'web/main.dart',
     'web/third_party/trace_viewer_full.html',
     'web/timeline.html',
     'web/timeline.js',
     'web/timeline_message_handler.js',
   ],
 }