Revert "Build Observatory with runtime"

runtime/bin/vmservice/observatory/lib/src/app/settings.dart

 // Copyright (c) 2014, 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.
 
 part of app;
 
 /// Static settings database.
 class _Settings {
   static Storage _storage = window.localStorage;
 
@@ skipping 25 matching lines @@
   void set(String key, dynamic value) {
     var fullKey = _fullKey(key);
     _Settings.set(fullKey, value);
   }
 
   dynamic get(String key) {
     var fullKey = _fullKey(key);
     return _Settings.get(fullKey);
   }
 }