增加selectivizr ie6-8支持css选择器。
<script type="text/javascript" src="[JS library]"></script>
<!--[if (gte IE 6)&(lte IE 8)]>
  <script type="text/javascript" src="selectivizr.js"></script>
  <noscript><link rel="stylesheet" href="[fallback css]" /></noscript>
<![endif]-->