A way to access the browser information with an implicit object in EL (such as ${zk.ie >= 9})

Right now, users have to import a TLD library and then use c:browser or similar. It is more convenient if the users could use the implicit object directly, such as ${zk.gecko == 7}.

Unlike JavaScript, EL won't convert double to boolean automatically, so, to check a particular browser: ${zk.ie > 0 || zk.opera > 0}