Function lineNumberFor

static/editor.md/lib/codemirror/lib/codemirror.js:604–606

(options, i)

  }

  function lineNumberFor(options, i) {
    return String(options.lineNumberFormatter(i + options.firstLineNumber));
  }

  // Computes display.scroller.scrollLeft + display.gutters.offsetWidth,
  // but using getBoundingClientRect to get a sub-pixel-accurate