**TypeScript Version:** 2.6.3 lib.dom.d.ts has alt attribute for HTMLObjectElement: https://github.com/Microsoft/TypeScript/blob/5b5a00745997768fad7d3a4c98931af179fa277a/lib/lib.dom.d.ts#L5981-L5986 This is not in [HTML Standard](https://html.spec.whatwg.org/multipage/iframe-embed-object.html#the-object-element), Firefox or Chrome available.
TypeScript Version: 2.6.3
lib.dom.d.ts has alt attribute for HTMLObjectElement:
https://github.com/Microsoft/TypeScript/blob/5b5a00745997768fad7d3a4c98931af179fa277a/lib/lib.dom.d.ts#L5981-L5986
This is not in HTML Standard, Firefox or Chrome available.