Use case :

I'm working on a library that provides cross-browser support for some of the most interesting features of web components.

I used the html-shiv to add support in IE8- for the 'template' and 'content' tag.

When using Sizzle with the selector 'content[select]' to select 'content' tags that have a 'select' attribute, Sizzle fails to produce the correct result in IE8.

I did, however, get the expected result when disabling native support for doc.querySelectorAll in IE8, by doing the following :

See the following code on line 608 :

if ( (support.qsa = rnative.test( doc.querySelectorAll )) ) {
    [ ... ]
}

I replaced it with this :

try {
   document.querySelectorAll('html:root');
   var querySelectorSupported = true;
} catch (err) {
   var querySelectorSupported = false;
}
if ((support.qsa = querySelectorSupported)) {
    [ ... ]
}

For me, this solves the problem. However, I guess there are better ways to solve this bug, which is why I'm logging a ticket rather than submitting a patch.