iframe自适应高度详解
主页面代码示例：
<iframe id="frame_content" src="iframe_b.html" scrolling="no" frameborder="0"></iframe>
<script type="text/javascript">
function reinitIframe(){
var iframe = document.getElementById("frame_content");
try{
iframe.height = iframe.contentWindow.document.documentElement.scrollHeight;
}catch (ex){}
}
window.setInterval("reinitIframe()", 200);
</script>
