Pretty sure it's via the Firebug add-on for Firefox.
At least according to Kyatric:
"This appear to make my firebug respond.
Meaning that your plugin works for Chrome and FF"
I confirm it works on FF, but I keep getting a constant stream of "GET localhost/_reloadpoll_ where the X's are random numbers. Works fine otherwise.
EDIT: NVM, just disable "Show XMLHtmlRequests".
Thanks a LOT! Can't express enough how useful this is. Might want to make this type of thing official IMHO.