Removed non standard "filter" CSS property.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@7929 e93f8b46-1217-0410-a6f0-8f06a7374b81

public/stylesheets/application.css

@@ -551,7 +551,6 @@ font-weight:bold;
 text-align:center;
 padding:0.6em;
 z-index:100;
-filter:alpha(opacity=50);
 opacity: 0.5;
 }