This test does the following:
1. Load a page, trigger an XHR.
2. Reload the page.
3. Dump the http readers for the reload of the XHR.

The XHR is trigger after onload has fired. There should not be an HTTP_CACHE_CONTROL header forcing reload, so an http cache could load the resource without contacting the server.
The test passes if there is no HTTP_CACHE_CONTROL header displayed below.