Fix case when <script> or <style> contains a <!⁠[CDATA[…]]> section

[ExE-Boss]

When <script> or <style> contains a <!⁠[CDATA[…]]> section then code inside the section isn’t properly highlighted:

<script type="application/javascript"><![CDATA[
let stuff;
alert("</script>");
]]></script>

<style type="text/css"><![CDATA[
.stuff {
	…
}
]]></style>

See for a live example:

• https://developer.mozilla.org/docs/User:ExE-Boss/Prism_issues#CDATA_in_script_or_style