Verify that correct number of arguments was passed.

sdk/lib/indexed_db/dart2js/indexed_db_dart2js.dart

 library dart.dom.indexed_db;
 
 import 'dart:async';
 import 'dart:html';
 import 'dart:html_common';
 import 'dart:typed_data';
 import 'dart:_js_helper' show Creates, Returns, JSName, Null;
 import 'dart:_foreign_helper' show JS;
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ skipping 893 matching lines @@
   @DocsEditable
   Request $dom_count([key_OR_range]) native;
 
   @DomName('IDBObjectStore.createIndex')
   @DocsEditable
   Index $dom_createIndex(String name, keyPath, [Map options]) {
     if ((keyPath is List<String> || keyPath == null) && !?options) {
       List keyPath_1 = convertDartToNative_StringArray(keyPath);
       return _$dom_createIndex_1(name, keyPath_1);
     }
-    if ((keyPath is List<String> || keyPath == null)) {
+    if ((keyPath is List<String> || keyPath == null) && ?options) {
       List keyPath_2 = convertDartToNative_StringArray(keyPath);
       var options_3 = convertDartToNative_Dictionary(options);
       return _$dom_createIndex_2(name, keyPath_2, options_3);
     }
     if ((keyPath is String || keyPath == null) && !?options) {
       return _$dom_createIndex_3(name, keyPath);
     }
-    if ((keyPath is String || keyPath == null)) {
+    if ((keyPath is String || keyPath == null) && ?options) {
       var options_4 = convertDartToNative_Dictionary(options);
       return _$dom_createIndex_4(name, keyPath, options_4);
     }
     throw new ArgumentError("Incorrect number or type of arguments");
   }
   @JSName('createIndex')
   @DomName('IDBObjectStore.createIndex')
   @DocsEditable
   Index _$dom_createIndex_1(name, List keyPath) native;
   @JSName('createIndex')
@@ skipping 318 matching lines @@
 // Copyright (c) 2012, 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.
 
 
 @DocsEditable
 @DomName('IDBAny')
 @deprecated // nonstandard
 abstract class _IDBAny native "IDBAny" {
 }