Fix time-out in testOnFormResubmission

 Bug 6419734
 After loading a page, the javascript within the page resubmits
 it. The detector first waits for the page to load and then
 waits for the second load. If it happens that the javascript
 resubmits the page before the first load is detected, it will
 not detect the first load before the second one starts and will
 not detect all the signals of the second load. The second wait
 will then hang while waiting. This CL causes the javscript to
 wait longer to ensure that the first page load is detected
 prior to resubmitting the page.

Change-Id: I0cbad44406fc4f725ad68f78dae0718c7ea2f39c