function createTestNode (family, attributes) {
  var span = document.createElement('span');
  span.setAttribute('data-fontfamily', family);
  span.style.cssText = 'position:absolute; left:-5000px; top:-5000px; visibility:hidden;' +
    'font-size:100px; font-family:"' + family + '", Helvetica;font-weight: ' + attributes.weight + ';' +
    'font-style:' + attributes.style + ';';
  span.innerHTML = 'BESs';
  return span;
}
Helper method for created a hidden <span> with a given font.
Uses TypeKit's default test string, which is said to result
in highly varied measured widths when compared to the default font.
@internal