Fix potential CORS issues with webroot transport on BYOND 516 (#90256)

## About The Pull Request

css also needs `node.crossOrigin = 'anonymous';`, at least in my case.

credit to @hry-gh for pointing this out to me

## Why It's Good For The Game

bluescreen = bad
working = good

## Changelog
🆑 Absolucy, hry-gh
fix: Fixed a potential bluescreen error relating to stylesheets on BYOND
516.
/🆑

tgui/public/tgui.html

@@ -314,6 +314,7 @@
       var node = document.createElement('link');
       node.type = 'text/css';
       node.rel = 'stylesheet';
+      node.crossOrigin = 'anonymous';
       node.href = url;
       // Temporarily set media to something inapplicable
       // to ensure it'll fetch without blocking render