CSSSyntax doesn't parse numeric range restrictions correctly

[ferdnyc]

The CSS grammar supports range restrictions for numeric values of the form <integer [0,10]> (signifying a number that can have any integer value from 0...10 inclusive). Range annotations are used in two places in the MDN syntaxes.json file, so far:

1. In font-weight-absolute (since Restrict font-weight-absolute values to numbers in the 1...1000 range data#420)
2. In cubic-bezier-timing-function (since restrict cubic-bezier-timing-function abscissas to be in range [0,1] data#416)

However, kumascript/macros/CSSSyntax.ejs mis-parses those annotations, resulting in corrupted HTML source such as this example from font-weight§Formal syntax:

<pre class="syntaxbox notranslate">
<a href="#font-weight-absolute">&lt;font-weight-absolute&gt;</a> 
<a href="/en-US/docs/CSS/Value_definition_syntax#Single_bar" 
title="Single bar: exactly one of the entities must be present">|</a>
 bolder 
<a href="/en-US/docs/CSS/Value_definition_syntax#Single_bar" 
title="Single bar: exactly one of the entities must be present">|</a>
 lighter
<p style="font-family: Open Sans,Arial,sans-serif; margin: 10px 0 0 0;">where <br>
<code style='font-family: Consolas,Monaco,"Andale Mono",monospace;'>
<span id="font-weight-absolute">&lt;font-weight-absolute&gt;</span>
 = normal 
<a href="/en-US/docs/CSS/Value_definition_syntax#Single_bar" 
title="Single bar: exactly one of the entities must be present">|</a>
 bold 
<a href="/en-US/docs/CSS/Value_definition_syntax#Single_bar" 
title="Single bar: exactly one of the entities must be present">|</a>
 &lt;number 
&lt;a href="/en-US/docs/CSS/Value_definition_syntax#Brackets" 
title="Brackets: enclose several entities, combinators, and multipliers to 
transform them as a single component"&gt;
[1,1000
<a href="/en-US/docs/CSS/Value_definition_syntax#Brackets" 
title="Brackets: enclose several entities, combinators, and multipliers to 
transform them as a single component">]</a>
&gt;
</code>
</p></pre>

This renders as:

<font-weight-absolute> | bolder | lighter
where 
<font-weight-absolute> = normal | bold | <number <a href="/en-
US/docs/CSS/Value_definition_syntax#Brackets" title="Brackets: enclose several 
entities, combinators, and multipliers to transform them as a single component">
[1,1000]>

Instead of the expected:

<font-weight-absolute> | bolder | lighter
where 
<font-weight-absolute> = normal | bold | <number [1,1000]>