// Only certain elements can match :enabled or :disabled
// https://html.spec.whatwg.org/multipage/scripting.html#selector-enabled
// https://html.spec.whatwg.org/multipage/scripting.html#selector-disabled

// Check for inherited disabledness on relevant non-disabled elements:
// * listed form-associated elements
//   https://html.spec.whatwg.org/multipage/forms.html#category-listed
// * option elements
//   https://html.spec.whatwg.org/multipage/forms.html#concept-option-disabled
return "form" in elem && elem.disabled === false ?

    // Support: IE 6 - 11
    // Use the shortcut property, which already covers inheritance
    elem.isDisabled === disabled ||
    elem.isDisabled !== !disabled && ("label" in elem ?

        // Option elements defer to a parent optgroup if present
        (elem.parentNode && "label" in elem.parentNode ?
            elem.parentNode.disabled === disabled :
            elem.disabled === disabled) :

        // All others defer to ancestor fieldsets if present
        disabledAncestor( elem ) === disabled
    ) :

    // Check other disableable elements for direct disabledness
    // Some victims get caught in our net (label, legend, menu, track),
    // but they shouldn't have the property anyway.
    "form" in elem && elem.disabled === disabled ||
    "label" in elem && elem.disabled === disabled;