add getElementsByClassName method to IE browsers (<9) that do not support it

ElementsByClassName_For_IE.js

//add getElementsByClassName method to IE browsers that do not support it
if (!document.getElementsByClassName) {
  document.getElementsByClassName = function (cn) {
  var rx = new RegExp("\\b" + cn + "\\b"), allT = document.getElementsByTagName("*"), allCN = [], i = 0, a;
    while (a = allT[i++]) {
      if (a.className && a.className.indexOf(cn) + 1) {
      if(a.className===cn){ allCN[allCN.length] = a; continue; }
      rx.test(a.className) ? (allCN[allCN.length] = a) : 0;
      }
    }
  return allCN;
  }
}