declare some properties in the node constructor so that they're copied in clone

lib/scope.js

@@ -231,9 +231,9 @@ AST_Scope.DEFMETHOD("next_mangled", function(){
     out: while (true) {
         var m = base54(++this.cname);
         if (!is_identifier(m)) continue; // skip over "do"
-        // if it's for functions or variables, we must ensure that the
-        // mangled name does not shadow a name from some parent scope
-        // that is referenced in this or in inner scopes.
+        // we must ensure that the mangled name does not shadow a name
+        // from some parent scope that is referenced in this or in
+        // inner scopes.
         for (var i = n; --i >= 0;) {
             var sym = ext[i];
             var name = sym.mangled_name || sym.name;