我通过遵循以下帖子. 简而言之，通过使用扩展，也可以使用firefox将javascript代码注入Web页面. 为了避免浪费其他用户的时间，主要文件为:

I found the solution to the problem by following this post. In few words, by using an extensions it is possible to inject javascript code into the Web page also with firefox. In order to avoid a waste of time for the other users, the main files are:

Python文件:selenium + firefox

Python file: selenium+firefox

import json
import os
import sys

from selenium import webdriver
from selenium.common.exceptions import NoSuchElementException
from selenium.webdriver.firefox.firefox_profile import AddonFormatError

# Patch in support for WebExtensions in Firefox.
# See: https://intoli.com/blog/firefox-extensions-with-selenium/
class FirefoxProfileWithWebExtensionSupport(webdriver.FirefoxProfile):
    def _addon_details(self, addon_path):
        try:
            return super()._addon_details(addon_path)
        except AddonFormatError:
            try:
                with open(os.path.join(addon_path, "manifest.json"), "r") as f:
                    manifest = json.load(f)
                    return {
                        "id": manifest["applications"]["gecko"]["id"],
                        "version": manifest["version"],
                        "name": manifest["name"],
                        "unpack": False,
                    }
            except (IOError, KeyError) as e:
                raise AddonFormatError(str(e), sys.exc_info()[2])

profile_folder="profile_path"
profile=FirefoxProfileWithWebExtensionSupport(profile_folder)
extension_directory="extension"
profile.add_extension(extension_directory)
# firefox dev it is necessary for custom profile, not for standard one
firefox_binary="/usr/bin/firefox-dev"
options=webdriver.FirefoxOptions()
# firefox 56+ headless mode https://developer.mozilla.org/en-US/Firefox/Headless_mode
options.set_headless(True)
driver=webdriver.Firefox(options=options, firefox_profile=profile, firefox_binary=firefox_binary)

test_url="https://intoli.com/blog/not-possible-to-block-chrome-headless/chrome-headless-test.html";
driver.get(test_url)

file="selenium-firefox-extension-profile-script-second-test.png"
driver.save_screenshot(file)

test_url="https://intoli.com/blog/making-chrome-headless-undetectable/chrome-headless-test.html";
driver.get(test_url)

file="selenium-firefox-extension-profile-script-first-test.png"
driver.save_screenshot(file)

driver.quit()

扩展文件:manifest.js和content.js

Extensions files: manifest.js and content.js

{
  "manifest_version": 2,
  "name": "Smart Extension",
  "version": "1.0.0",
  "applications": {
    "gecko": {
      "id": "user@protonmail.com"
    }
  },
  "content_scripts": [
    {
      "matches": ["*://*/*"],
      "js": ["content.js"],
      "run_at": "document_start"
    }
  ]
}

var script=document.createElement("script");
script.src=browser.extension.getURL("myscript.js");
script.async=false;
document.documentElement.appendChild(script);

JavaScript文件:myscript.js

Javascript file: myscript.js

// overwrite the `languages` property to use a custom getter
Object.defineProperty(navigator, "languages", {
  get: function() {
    return ["en", "es"];
  }
});

// Overwrite the `plugins` property to use a custom getter.
Object.defineProperty(navigator, "plugins", {
  get: () => new Array(Math.floor(Math.random() * 6) + 1),
});

// Pass the Webdriver test
Object.defineProperty(navigator, "webdriver", {
  get: () => false,
});

// hairline: store the existing descriptor
const elementDescriptor=Object.getOwnPropertyDescriptor(HTMLElement.prototype, "offsetHeight");

// redefine the property with a patched descriptor
Object.defineProperty(HTMLDivElement.prototype, "offsetHeight", {
    ...elementDescriptor,
  get: function() {
    if (this.id === "modernizr") {
      return 1;
    }
    return elementDescriptor.get.apply(this);
  },
});

["height", "width"].forEach(property => {
  // store the existing descriptor
  const imageDescriptor=Object.getOwnPropertyDescriptor(HTMLImageElement.prototype, property);

  // redefine the property with a patched descriptor
  Object.defineProperty(HTMLImageElement.prototype, property, {
    ...imageDescriptor,
    get: function() {
      // return an arbitrary non-zero dimension if the image failed to load
      if (this.complete && this.naturalHeight == 0) {
        return 24;
      }
      // otherwise, return the actual dimension
      return imageDescriptor.get.apply(this);
    },
  });
});

const getParameter=WebGLRenderingContext.getParameter;
WebGLRenderingContext.prototype.getParameter=function(parameter) {
  // UNMASKED_VENDOR_WEBGL WebGLRenderingContext.prototype.VENDOR
  if (parameter === 37445) {
    return "Intel Open Source Technology Center";
  }
  // UNMASKED_RENDERER_WEBGL WebGLRenderingContext.prototype.RENDERER
  if (parameter === 37446) { 
    return "Mesa DRI Intel(R) Ivybridge Mobile";
  }
  return getParameter(parameter);
};

这对于图形模式下的所有测试都适用，而在无头模式下，除WebGL测试外的所有测试似乎都对错误.

This works well for all tests in graphical mode while in headless mode all tests except WebGL test which seems affect to a bug.