Add dummy dart:html library for documentation.

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