Firefox 220.127.116.11 on Mac allows XMLHttpRequest.send() calls to succeed without any arguments. Firefox on Win (18.104.22.168 tested) and Linux (22.214.171.124 tested) as well as Camino 1.5.4 and K-Meleon 1.1.3 all return an exception: [Exception... "Not enough arguments" nsresult: "0x80570001 (NS_ERROR_XPC_NOT_ENOUGH_ARGS)" location: "JS frame :: http://localhost/~gkolanek/xhr/get.html :: test :: line 29" data: no] Either Firefox on Mac is wrong or Firefox on the other platforms along with the embedders are. The result should certainly be consistent. (Note that both Safari and Opera on both Mac and Windows allow send() calls without any arguments, further confusing the picture.)
Created attachment 295936 [details] XHTML Testcase
I was wrong after all. XMLHttpRequest.send() only succeeds in Firefox when Firebug is enabled.