Function indexOf

static/editor.md/lib/codemirror/addon/mode/simple.js:183–185

(val, arr)

  }

  function indexOf(val, arr) {
    for (var i = 0; i < arr.length; i++) if (arr[i] === val) return true;
  }

  function indentFunction(states, meta) {
    return function(state, textAfter, line) {