Add dummy dart:html library for documentation.

lib/html/doc/interface/SQLError.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 SQLError
+interface SQLError {
+
+  static final int CONSTRAINT_ERR = 6;
+
+  static final int DATABASE_ERR = 1;
+
+  static final int QUOTA_ERR = 4;
+
+  static final int SYNTAX_ERR = 5;
+
+  static final int TIMEOUT_ERR = 7;
+
+  static final int TOO_LARGE_ERR = 3;
+
+  static final int UNKNOWN_ERR = 0;
+
+  static final int VERSION_ERR = 2;
+
+  /** @domName SQLError.code */
+  final int code;
+
+  /** @domName SQLError.message */
+  final String message;
+}