function createInput(rootDocument) {
  var input = rootDocument.createElement('input');
  input.className = 'htCheckboxRendererInput';
  input.type = 'checkbox';
  input.setAttribute('autocomplete', 'off');
  input.setAttribute('tabindex', '-1');
  return input.cloneNode(false);
}
Create input element.

@param {Document} rootDocument
@returns {Node}