Tampermonkey: API GM_download can't use with Firefox browser

[tick97115115]

(Please fill out the issue template with your details)
I was trying to download some blob object, but GM_donwload doesn't work.

• I has been adjust the download option to "browser API"
• saveAs setting :true

Expected Behavior

• download window popup

Actual Behavior

• Not any download window popup or download mission start.

Specifications

• Firefox: (76.0.1)
• TM: (4.10.6112)
• OS: (Windows10 18363.836)

Script

// ==UserScript==
// @name MyName
// @namespace http://mywebsite.com
// @Version 1.0
// @description try to take over the world!
// @author Me
// @match http://mywebsite.com/*
// @require http://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js
// @include https://mywebsite.com/*
// @grant GM_download
// ==/UserScript==

let text = "String";
let data = new Blob([text],{type:'text/plain'});
let arg = {
    url: URL.createObjectURL(data),
    name: "textInfo.txt",
    saveAs: true,
}
GM_download(arg)

[tick97115115]

An additional info:
The GM_download API was worked fine with Edge browser.

[mkckr0]

I also have this problem.

[derjanb]

Should be fixed at TM BETA 4.11.6113 (https://www.tampermonkey.net/index.php?browser=firefox)