venk-subscripts.uc.js

// ==UserScript==
// @name Debug subscripts with Venkman
// @description Allows you to debug subscripts with Venkman
// @include chrome://venkman/content/venkman.xul
// @author mooz
// @license MIT
// ==/UserScript==

["_getChannelForURL", "loadURLNow", "loadURLAsync"].forEach(function (func) {
    if (func in window && !window[func].original) {
        let original = window[func];

        window[func] = function () {
            if (arguments[0].indexOf(" -> ") !== -1)
                arguments[0] = arguments[0].split(" -> ")[1];

            return original.apply(this, arguments);
        };

        window[func].original = original;
    }
});