Even before that in Java with GWT.

Any programming language can be used to produce HTML, but here – with Scala, Kotlin and Swift – we're talking about something more specific: using an internal DSL to write concise, simple and somewhat declarative code that describes the HTML tree.

Java definitely can't (reasonably, sensibly, practically) do that. GWT seems to be using XML from what I can tell: http://www.gwtproject.org/doc/latest/polymer-tutorial/widget...

And probably before that Common Lisp