Right now we use codemirror's JavaScript mode on the website but there's a JSX mode now so we should start using that instead.

cx.state.context = {prev: cx.state.context, vars: cx.state.localVars};
    cx.state.localVars = defaultVars;
  }
  function popcontext() {
    cx.state.localVars = cx.state.context.vars;
    cx.state.context = cx.state.context.prev;
  }
  function pushlex(type, info) {
    var result = function() {
      var state = cx.state;
      state.lexical = new JSLexical(state.indented, cx.stream.column(), type, null, state.lexical, info);
    };
    result.lex = true;
    return result;
  }
  function poplex() {
    var state = cx.state;
    if (state.lexical.prev) {
      if (state.lexical.type == ")")
        state.indented = state.lexical.indented;
      state.lexical = state.lexical.prev;
    }
  }
  poplex.lex = true;
  function expect(wanted) {