Compatible with facebook HHVM 3.1

This patch to make HTML5 compatible with HHVM contains also workaround to avoid this https://github.com/facebook/hhvm/issues/2962
```html
<script>
//<![CDATA[
alert(1)
//]]>
</script>
```
`$ele->data` contains just:
```
//
alert(1)
//