Delightful DOM

From the browser, open the developer tools (press Command+Alt+J (Mac) or F12 (Windows)). Go to the Console, paste below code:

$('<style type="text/css">a:after{content:" ("attr(href)") "}</style>').appendTo(document.head);
var css = 'a:after{content:" ("attr(href)") "}',
    head = document.head || document.getElementsByTagName('head')[0],
    style = document.createElement('style');
style.type = 'text/css';
if (style.styleSheet){
  style.styleSheet.cssText = css;
} else {
  style.appendChild(document.createTextNode(css));
}
head.appendChild(style);