Add dummy dart:html library for documentation.

lib/html/doc/interface/DOMPluginArray.dart

Index: lib/html/doc/interface/DOMPluginArray.dart
diff --git a/lib/html/doc/interface/DOMPluginArray.dart b/lib/html/doc/interface/DOMPluginArray.dart
new file mode 100644
index 0000000000000000000000000000000000000000..3ac20427f2b652e158e08d72da99e89348d50a01
--- /dev/null
+++ b/lib/html/doc/interface/DOMPluginArray.dart
@@ -0,0 +1,21 @@
+// 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: Do not edit - generated code.
+
+/// @domName DOMPluginArray
+interface DOMPluginArray {
+
+  /** @domName DOMPluginArray.length */
+  final int length;
+
+  /** @domName DOMPluginArray.item */
+  DOMPlugin item(int index);
+
+  /** @domName DOMPluginArray.namedItem */
+  DOMPlugin namedItem(String name);
+
+  /** @domName DOMPluginArray.refresh */
+  void refresh(bool reload);
+}