`unsafeWindow` polyfill (for use in user scripts)

unsafeWindow.user.js

// ==UserScript==
// @name Emulate `unsafeWindow` in browsers that don’t support it.
// ==/UserScript==

// http://mths.be/unsafewindow
window.unsafeWindow || (
	unsafeWindow = (function() {
		var el = document.createElement('p');
		el.setAttribute('onclick', 'return window;');
		return el.onclick();
	}())
);

// You can now use `unsafeWindow`, ehm, safely.
console.log(unsafeWindow);
// If the current document uses a JavaScript library, you can use it in
// your user script like this:
console.log(unsafeWindow.jQuery);