Add dummy dart:html library for documentation.

lib/html/doc/interface/SVGStringList.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 SVGStringList
+interface SVGStringList {
+
+  /** @domName SVGStringList.numberOfItems */
+  final int numberOfItems;
+
+  /** @domName SVGStringList.appendItem */
+  String appendItem(String item);
+
+  /** @domName SVGStringList.clear */
+  void clear();
+
+  /** @domName SVGStringList.getItem */
+  String getItem(int index);
+
+  /** @domName SVGStringList.initialize */
+  String initialize(String item);
+
+  /** @domName SVGStringList.insertItemBefore */
+  String insertItemBefore(String item, int index);
+
+  /** @domName SVGStringList.removeItem */
+  String removeItem(int index);
+
+  /** @domName SVGStringList.replaceItem */
+  String replaceItem(String item, int index);
+}