Feature request: add online tool (or babel REPL setup) to convert from JSX to htm

While converting a project from JSX to htm i missed a online tool (or a codepen/fiddlejs or babel repl setup) to run babel with babel-plugin-transform-jsx-to-htm

I tried to configure [Babel REPL](https://babeljs.io/repl) adding @babel/plugin-syntax-jsx and babel-plugin-transform-jsx-to-htm plugins with no luck (a bug in Babel REPL?)

Start by reproducing the requested setup in the Babel REPL with @babel/plugin-syntax-jsx and babel-plugin-transform-jsx-to-htm, then compare a CodePen or JSFiddle setup. Done should be a working online JSX-to-htm conversion path or a documented Babel REPL configuration.

索引モデルが issue の本文から書いたものです。