All documents recognized as HTML in Chrome >= 32

[loganfsmyth]

The isHTMLDocument feature detection flag is true for XML documents in Chrome 32, so any attempt to use a function that triggers setDocument on an XML element throws "Uncaught TypeError: Cannot set property 'display' of null".

e.g. http://jsfiddle.net/TcyEW/1

The offending code is https://github.com/mootools/slick/blob/master/Source/Slick.Finder.js#L84

// on non-HTML documents innerHTML and getElementsById doesnt work properly
try {
        testNode.innerHTML = '<a id="'+id+'"></a>';
        features.isHTMLDocument = !!document.getElementById(id);
} catch(e){}

This is caused by:
Move 'innerHTML': https://code.google.com/p/chromium/issues/detail?id=311080
Wrong 'id': https://code.google.com/p/chromium/issues/detail?id=315168

[arian]

Thanks, so because of https://code.google.com/p/chromium/issues/detail?id=311080 innerHTML actually works on all DOM elements...

We could also check if testNode.style or some other property of HTMLElement (http://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-58190037)is available. Or use Object.prototype.toString(testNode).slice(1, 5) == 'HTML'.

[loganfsmyth]

Yep, and innerHTML is actually already works like that on Firefox, but it doesn't fail because on Firefox the getElementById returns null because the id attribute isn't defined as an ID attribute in the DTD of most documents.