Add dummy dart:html library for documentation.

lib/html/doc/interface/PerformanceNavigation.dartdoc

Index: lib/html/doc/interface/PerformanceNavigation.dartdoc
diff --git a/lib/html/doc/interface/PerformanceNavigation.dartdoc b/lib/html/doc/interface/PerformanceNavigation.dartdoc
new file mode 100644
index 0000000000000000000000000000000000000000..7d22fab350e1c550d9d7c4659d0d9f35901a4db3
--- /dev/null
+++ b/lib/html/doc/interface/PerformanceNavigation.dartdoc
@@ -0,0 +1,25 @@
+// 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 PerformanceNavigation
+interface PerformanceNavigation {
+
+  static final int TYPE_BACK_FORWARD = 2;
+
+  static final int TYPE_NAVIGATE = 0;
+
+  static final int TYPE_RELOAD = 1;
+
+  static final int TYPE_RESERVED = 255;
+
+  /** @domName PerformanceNavigation.redirectCount */
+  final int redirectCount;
+
+  /** @domName PerformanceNavigation.type */
+  final int type;
+}