Note: After saving, you have to bypass your browser's cache to see the changes. Internet Explorer: press Ctrl-F5, Mozilla: hold down Shift while clicking Reload (or press Ctrl-Shift-R), Opera/Konqueror: press F5, Safari: hold down Shift + Alt while clicking Reload, Chrome: hold down Shift while clicking Reload.
var UploadForm_forcebasic = true;

// Replacer
function wpTextboxReplace(){
  var s = prompt("Search regexp:");
  if(s){
    var r = prompt("Replace /"+s+"/ with:");
    if(!r && r != '') return;
    var txt = document.editform.wpTextbox1;
    txt.value = txt.value.replace(new RegExp(s, "mg"), r);
  }
}
$(function(){
  if(document.forms.editform){
    mw.util.addPortletLink('p-cactions', 'javascript:wpTextboxReplace()', 'Replace', 'ca-replace',
                   'Regexp replace for the edit window', 'R', document.getElementById('ca-history'));
  }
});
mw.loader.load('https://commons.wikimedia.org/w/index.php?title=User:Patstuart/Flickrreview.js'
+ '&action=raw&ctype=text/javascript');