googlecleaner.user.js

// ==UserScript==
// @name           Clean Google links
// @namespace      http://d.hatena.ne.jp/MillyC/
// @description    clean links in Google search result page (remove "onmousedown" attribute).
// @include        http://www.google.com/search?*
// @include        https://www.google.com/search?*
// @include        http://www.google.co.*/search?*
// @include        https://www.google.co.*/search?*
// @grant          none
// ==/UserScript==

document.body.addEventListener('mousedown', function(event){
  var el = event.target;
  if (el && el.tagName == 'A') {
    el.removeAttribute('onmousedown');
  }
}, true);