nitrogen.js "Object expected" error in IE8

In Internet Explorer 8, NitrogenClass.prototype.$make_id() triggers an error:

Object expected nitrogen.js, line 110 character 2

The reason is that the "matches" variable is null when match doesn't match anything, and apply doesn't expect that. We can patch this with:

diff --git a/apps/nitrogen/www/nitrogen.js b/apps/nitrogen/www/nitrogen.js
index 3c9e17d..b9a2c5e 100644
--- a/apps/nitrogen/www/nitrogen.js
+++ b/apps/nitrogen/www/nitrogen.js
@@ -107,7 +107,9 @@ NitrogenClass.prototype.$make_id = function(element) {
     var re = new RegExp("\.wfid_(.[^\\s]*)", "g");
     while(element && element.className) {
        var matches = element.className.match(/wfid_([^\s])+/g);
-       a.unshift.apply(a, matches);
+       if (matches) {
+           a.unshift.apply(a, matches);
+       }
        element = element.parentNode;           
     }

As a matter of code hygiene, we can probably also remove the "var re = ..." line, since it doesn't appear to be used.