This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://greasyfork.org/scripts/2963-gif-js/code/gifjs.js?version=8596
* I didn't create this, just modified it to allow it running in userscript.
* Auther : https://github.com/jnordberg/gif.js
* source and source map from
* use GIF_worker_URL to assign the worker script path