:focus-visible not matched unless element has autofocus property set

[mattclough1]

I'm trying my best to follow the source code, but the logic for the :focus-visible selector:

nwsapi/src/nwsapi.js

Lines 1098 to 1103 in 088475f

	case 'focus-visible':
	source = 'hasFocus' in doc ?
	'if(s.isFocusable(e)){' +
	'n=s.doc.activeElement;if(e!==n){while(e){e=e.parentElement;if(e===n)break;}}}' +
	'if((e===n&&e.autofocus)){' + source + '}' : source;
	break;

seems to only match an element if it's the same element as document.activeElement and has the property autofocus. If this is true, why? For context, some code I'm testing that uses .match(':focus-visible') matches in the browser, but fails to match in JSDOM unless I add autofocus to the element. I don't think this property is part of the general heuristics that browsers use to determine a match on this selector.