Embora não seja uma solução do Firefox para o seu problema, que tal uma solução alternativa?
No Opera, tudo o que você precisa é de um regex simples que encontre e substitua o script. Nenhuma extensão complexa, apenas um arquivo JS de usuário simples, que ficaria assim.
Disable redirection 1.00.js
:
// ==UserScript==
// @name Disable redirection
// @version 1.00
// @description Disables redirection.
// @namespace http://superuser.com/questions/353339/firefox-disable-window-location-on-website/511703#511703
// @copyright 2012
// @author XP1
// @homepage https://github.com/XP1/
// @license Apache License, Version 2.0; http://www.apache.org/licenses/LICENSE-2.0
// @include http*://example.com/*
// @include http*://*.example.com/*
// ==/UserScript==
/*
* Copyright 2012 XP1
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*jslint browser: true, vars: true, maxerr: 50, indent: 4 */
(function (opera) {
"use strict";
var isReplaced = false;
function replaceJs(userJsEvent) {
if (isReplaced) {
return;
}
var element = userJsEvent.element;
element.text = element.text.replace(/window\.location = "someotherpage\.html";/g, "");
isReplaced = true;
}
opera.addEventListener("BeforeScript", function listener(userJsEvent) {
if (isReplaced) {
opera.removeEventListener("BeforeScript", listener, false);
return;
}
replaceJs(userJsEvent);
}, false);
}(this.opera));