fix arguments keyword used in our helper method

lib/src/codegen/js_names.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dev_compiler.src.codegen.js_names;
 
 import 'package:dev_compiler/src/js/js_ast.dart';
 
 /// Marker subclass for temporary variables.
 /// We treat these as being in a different scope from other identifiers, and
@@ skipping 22 matching lines @@
   final renames = new Map<String, String>();
 
   JSNamer(Node node) {
     node.accept(new _NameCollector(usedNames));
   }
 
   String getName(Identifier node) {
     var name = node.name;
     if (node is JSTemporary) {
       return _rename(name, valid: true);
-    } else if (invalidJSVariableName(name)) {
+    } else if (node.allowRename && invalidJSVariableName(name)) {
       return _rename(name, valid: false);
     }
     return name;
   }
 
   String _rename(String name, {bool valid}) {
     var candidate = renames[name];
     if (candidate != null) return candidate;
 
     // Try to use the temp's name, otherwise rename.
@@ skipping 76 matching lines @@
 /// In particular, "caller" "callee" and "arguments" cannot be used.
 bool invalidJSStaticMethodName(String name) {
   switch (name) {
     case "arguments":
     case "caller":
     case "callee":
       return true;
   }
   return false;
 }