See https://html.spec.whatwg.org/multipage/scripting.html#javascript-mime-type We don't support some of them according to: LayoutTests/http/tests/w3c/html/semantics/scripting-1/the-script-element/script-languages-02.html
<rdar://problem/22588195>
Created attachment 263343 [details] Patch
Comment on attachment 263343 [details] Patch Clearing flags on attachment: 263343 Committed r191268: <http://trac.webkit.org/changeset/191268>
All reviewed patches have been landed. Closing bug.