It would be nice if no-highlight took precedence

[ndw]

I learned about no-highlight in #842

This is a fairly minor issue, but in the interest of orthogonality, it would be nice if no-highlight took precedence over even a supported language. If, for example, Python is included as a supported language:

<pre class="no-highlight language-python">...

Syntax highlights the block using the Python highlighter.

I think something like:

if (block.classList.contains("no-highlight")) {
   return "no-highlight";
}

at the start of blockLanguage on line 95 would do it.