Add dummy dart:html library for documentation.

lib/html/doc/interface/StorageInfo.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 StorageInfo
+interface StorageInfo {
+
+  static final int PERSISTENT = 1;
+
+  static final int TEMPORARY = 0;
+
+  /** @domName StorageInfo.queryUsageAndQuota */
+  void queryUsageAndQuota(int storageType, [StorageInfoUsageCallback usageCallback, StorageInfoErrorCallback errorCallback]);
+
+  /** @domName StorageInfo.requestQuota */
+  void requestQuota(int storageType, int newQuotaInBytes, [StorageInfoQuotaCallback quotaCallback, StorageInfoErrorCallback errorCallback]);
+}