Simple failing case for php-spidermonkey mozjs17 port

test.php

<?php

$js = new JSContext();
$js->registerFunction('var_dump', 'var_dump');

$window = (object) [
	'foo' => function () {
		print 'foo';
	}
];

$js->assign('window', $window);

$script = <<<END

var_dump(typeof window.foo);

window.foo();

END;

$js->evaluateScript($script);