[CSS22] Double colons in Counters in elements with 'display: none'

Double colons in the example of “CSS22 12.4.3 Counters in elements with 'display: none'” seem like a bug. There are double colons between ‘h1’ and ‘before’:
>h1::before {
>    content: normal;
>    counter-increment: heading;
>}

-Bang Seongbeom