function defined(a) {
	return typeof a !== 'undefined';
}

function extend(child, parent, prototype) {
    var F = function() {};
    F.prototype = parent.prototype;
    child.prototype = new F();
    child.prototype.constructor = child;
	parent.prototype.constructor = parent;
    child._super = parent.prototype;
    if (prototype) {
        $.extend(child.prototype, prototype);
    }
}

var SUBST = [
    ['', ''],               // spec
    ['exit', 'cancel'],     // firefox & old webkits expect cancelFullScreen instead of exitFullscreen
    ['screen', 'Screen']    // firefox expects FullScreen instead of Fullscreen
];
var VENDOR_PREFIXES = ['', 'o', 'ms', 'moz', 'webkit'];

function native(obj, name) {
    var prefixed;

    if (typeof obj === 'string') {
        name = obj;
        obj = document;
    }

    for (var i = 0; i < SUBST.length; ++i) {
        name = name.replace(SUBST[i][0], SUBST[i][1]);
        for (var j = 0; j < VENDOR_PREFIXES.length; ++j) {
            prefixed = VENDOR_PREFIXES[j];
            prefixed += j === 0 ? name : name.charAt(0).toUpperCase() + name.substr(1);
            if (defined(obj[prefixed])) {
                return obj[prefixed];
            }
        }
    }

    return void 0;
}
function defined(a) {
	return typeof a !== 'undefined';
}

function extend(child, parent, prototype) {
    var F = function() {};
    F.prototype = parent.prototype;
    child.prototype = new F();
    child.prototype.constructor = child;
	parent.prototype.constructor = parent;
    child._super = parent.prototype;
    if (prototype) {
        $.extend(child.prototype, prototype);
    }
}

var SUBST = [
    ['', ''],               // spec
    ['exit', 'cancel'],     // firefox & old webkits expect cancelFullScreen instead of exitFullscreen
    ['screen', 'Screen']    // firefox expects FullScreen instead of Fullscreen
];

var VENDOR_PREFIXES = ['', 'o', 'ms', 'moz', 'webkit', 'webkitCurrent'];

function native(obj, name) {
    var prefixed;

    if (typeof obj === 'string') {
        name = obj;
        obj = document;
    }

    for (var i = 0; i < SUBST.length; ++i) {
        name = name.replace(SUBST[i][0], SUBST[i][1]);
        for (var j = 0; j < VENDOR_PREFIXES.length; ++j) {
            prefixed = VENDOR_PREFIXES[j];
            prefixed += j === 0 ? name : name.charAt(0).toUpperCase() + name.substr(1);
            if (defined(obj[prefixed])) {
                return obj[prefixed];
            }
        }
    }

    return void 0;
}
support for old-safari "webkitCurrentFullscreenElement" property [fixes #4]