Add dummy dart:html library for documentation.

lib/html/doc/interface/IDBRequest.dartdoc

+// 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.
+
+// WARNING:
+//   This file contains documentation that is merged into the real source.
+//   Do not make code changes here.
+
+/// @domName IDBRequest
+interface IDBRequest extends EventTarget {
+
+  /**
+   * @domName EventTarget.addEventListener, EventTarget.removeEventListener, EventTarget.dispatchEvent
+   */
+  IDBRequestEvents get on();
+
+  /** @domName IDBRequest.error */
+  final DOMError error;
+
+  /** @domName IDBRequest.errorCode */
+  final int errorCode;
+
+  /** @domName IDBRequest.readyState */
+  final String readyState;
+
+  /** @domName IDBRequest.result */
+  final Dynamic result;
+
+  /** @domName IDBRequest.source */
+  final Dynamic source;
+
+  /** @domName IDBRequest.transaction */
+  final IDBTransaction transaction;
+
+  /** @domName IDBRequest.webkitErrorMessage */
+  final String webkitErrorMessage;
+
+  /** @domName IDBRequest.addEventListener */
+  void $dom_addEventListener(String type, EventListener listener, [bool useCapture]);
+
+  /** @domName IDBRequest.dispatchEvent */
+  bool $dom_dispatchEvent(Event evt);
+
+  /** @domName IDBRequest.removeEventListener */
+  void $dom_removeEventListener(String type, EventListener listener, [bool useCapture]);
+}
+
+interface IDBRequestEvents extends Events {
+
+  EventListenerList get error();
+
+  EventListenerList get success();
+}