Clean variable __navigated_to_report when starting tests.

tools/page_cycler/database/start.js

-// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 document.title = 'page cycler';
 
+document.cookie = '__navigated_to_report=0; path=/';
 document.cookie = '__pc_done=0; path=/';
 document.cookie = '__pc_timings=; path=/';
 
 var options = location.search.substring(1).split('&');
 
 function getOption(name) {
   var r = new RegExp('^' + name + '=');
   for (var i = 0; i < options.length; i++) {
     if (options[i].match(r)) {
       return options[i].substring(name.length + 1);
@@ skipping 32 matching lines @@
   form.appendChild(input);
 
   document.body.appendChild(form);
 }
 
 renderForm();
 
 // should we start automatically?
 if (location.search.match('auto=1'))
   start();