fix AST_Scope.clone() (#2803)

fixes #2799

lib/ast.js

@@ -308,6 +308,13 @@ var AST_Scope = DEFNODE("Scope", "variables functions uses_with uses_eval parent
         enclosed: "[SymbolDef*/S] a list of all symbol definitions that are accessed from this scope or any subscopes",
         cname: "[integer/S] current index for mangling variables (used internally by the mangler)",
     },
+    clone: function(deep) {
+        var node = this._clone(deep);
+        if (this.variables) node.variables = this.variables.clone();
+        if (this.functions) node.functions = this.functions.clone();
+        if (this.enclosed) node.enclosed = this.enclosed.slice();
+        return node;
+    }
 }, AST_Block);
 
 var AST_Toplevel = DEFNODE("Toplevel", "globals", {

lib/utils.js

@@ -303,6 +303,13 @@ Dictionary.prototype = {
             ret.push(f(this._values[i], i.substr(1)));
         return ret;
     },
+    clone: function() {
+        var ret = new Dictionary();
+        for (var i in this._values)
+            ret._values[i] = this._values[i];
+        ret._size = this._size;
+        return ret;
+    },
     toObject: function() { return this._values }
 };
 Dictionary.fromObject = function(obj) {