Fixing CustomEvent.detail leaks.

sdk/lib/html/dart2js/html_dart2js.dart

 /// The Dart HTML library.
 ///
 /// For examples, see
 /// [Dart HTML5 Samples](https://github.com/dart-lang/dart-html5-samples)
 /// on Github.
 library dart.dom.html;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:_collection-dev' hide Symbol, deprecated;
@@ skipping 6030 matching lines @@
 // BSD-style license that can be found in the LICENSE file.
 
 // WARNING: Do not edit - generated code.
 
 
 @DomName('CustomEvent')
 class CustomEvent extends Event native "CustomEvent" {
   factory CustomEvent(String type,
       {bool canBubble: true, bool cancelable: true, Object detail}) {
 
-    final CustomEvent e = document.$dom_createEvent("CustomEvent");
+    final CustomEvent e = document.$dom_createEvent('CustomEvent');
+
+    detail = convertDartToNative_SerializedScriptValue(detail);
     e.$dom_initCustomEvent(type, canBubble, cancelable, detail);
 
     return e;
   }
   // To suppress missing implicit constructor warnings.
   factory CustomEvent._() { throw new UnsupportedError("Not supported"); }
 
+  dynamic get detail => convertNativeToDart_SerializedScriptValue(this._get_detail);
+  @JSName('detail')
   @DomName('CustomEvent.detail')
   @DocsEditable()
   @Creates('Null')
-  final Object detail;
+  final dynamic _get_detail;
 
   @JSName('initCustomEvent')
   @DomName('CustomEvent.initCustomEvent')
   @DocsEditable()
   void $dom_initCustomEvent(String typeArg, bool canBubbleArg, bool cancelableArg, Object detailArg) native;
 
 }
 // 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.
@@ skipping 23364 matching lines @@
       _position = nextPosition;
       return true;
     }
     _current = null;
     _position = _array.length;
     return false;
   }
 
   T get current => _current;
 }