Function scrollbarWidth

static/js/codemirror/codemirror.js:5054–5061

(measure)

  var knownScrollbarWidth;
  function scrollbarWidth(measure) {
    if (knownScrollbarWidth != null) return knownScrollbarWidth;
    var test = elt("div", null, null, "width: 50px; height: 50px; overflow-x: scroll");
    removeChildrenAndAdd(measure, test);
    if (test.offsetWidth)
      knownScrollbarWidth = test.offsetHeight - test.clientHeight;
    return knownScrollbarWidth || 0;
  }

  var zwspSupported;
  function zeroWidthElement(measure) {