// My rewritten version

(function(doc) {

	var metas = doc.querySelectorAll('meta[name="viewport"]'),
	    forEach = [].forEach;

	function fixMetas(isFirstTime) {
		var scales = isFirstTime === true ? ['1.0', '1.0'] : ['0.25', '1.6'];
		forEach.call(metas, function(el) {
			el.content = 'width=device-width,minimum-scale=' + scales[0] + ',maximum-scale=' + scales[1];
		});
	}

	fixMetas(true);

	doc.addEventListener('gesturestart', fixMetas, false);

}(document));