Merge pull request prototypejs#107 from superdav42/master

Add a space when we apply the `alpha` filter in old versions of IE so that we don't disrupt existing filters.

Author: savetheclocktower

src/prototype/dom/dom.js

@@ -2999,7 +2999,7 @@
     if (value < 0.00001) value = 0;
 
     style.filter = stripAlphaFromFilter_IE(filter) + 
-     'alpha(opacity=' + (value * 100) + ')';
+     ' alpha(opacity=' + (value * 100) + ')';
 
     return element;
   }