remove shorthand

lib/less/tree/rule.js

@@ -34,16 +34,4 @@ tree.Rule.prototype.makeImportant = function () {
                           this.index, this.inline);
 };
 
-tree.Shorthand = function (a, b) {
-    this.a = a;
-    this.b = b;
-};
-
-tree.Shorthand.prototype = {
-    toCSS: function (env) {
-        return this.a.toCSS(env) + "/" + this.b.toCSS(env);
-    },
-    eval: function () { return this }
-};
-
 })(require('../tree'));