When doing this GET synchronous ajax request in Firefox 27.0.1, Fedora 20, jQuery 1.11.0:

$.ajax(ajaxParam).then(
    function (r) {
        html = r.html;
    },
    function (jqXHR) {
        console.log(JSON.stringify([jqXHR, $.ajaxSettings, ajaxParam], null, 4));
    }
);

it works in Chrome 33.0.1750.146 for Linux but in Firefox no request is sent to the server and it errors out:

[
    {
        "readyState": 0,
        "status": 0,
        "statusText": "[Exception... \\"<no message>\\"  nsresult: \\"0x805e0006 (<unknown>)\\"  location: \\"JS frame :: http://example.com/static/jquery-1.11.0.min.js :: .send :: line 4\\"  data: no]"
    },
    {
        "url": "http://example.com/pt/BR",
        "type": "GET",
        "isLocal": false,
        "global": true,
        "processData": true,
        "async": true,
        "contentType": "application/x-www-form-urlencoded; charset=UTF-8",
        "accepts": {
            "*": "*/*",
            "text": "text/plain",
            "html": "text/html",
            "xml": "application/xml, text/xml",
            "json": "application/json, text/javascript",
            "script": "text/javascript, application/javascript, application/ecmascript, application/x-ecmascript"
        },
        "contents": {
            "xml": {},
            "html": {},
            "json": {},
            "script": {}
        },
        "responseFields": {
            "xml": "responseXML",
            "text": "responseText",
            "json": "responseJSON"
        },
        "converters": {
            "text html": true
        },
        "flatOptions": {
            "url": true,
            "context": true
        },
        "jsonp": "callback",
        "cache": false,
        "traditional": true,
        "dataType": "json"
    },
    {
        "url": "/advert/pt/BR",
        "data": {
            "realty_id": "2"
        },
        "async": false,
        "type": "GET"
    }
]