| Index: sdk/lib/html/dartium/html_dartium.dart | 
| diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart | 
| index 9fac5ebf309ec3345c470933c7c90b09061aa3ca..9307474d0d3881209c75ef003dc9fc0b86a98ad3 100644 | 
| --- a/sdk/lib/html/dartium/html_dartium.dart | 
| +++ b/sdk/lib/html/dartium/html_dartium.dart | 
| @@ -20146,6 +20146,10 @@ class HtmlDocument extends Document { | 
| js.JsNative.setProperty(elemProto, 'createdCallback', js.allowInteropCaptureThis(($this) { | 
| // The created callback has already been called by the very act of passing a JS | 
| // custom element from JS to Dart. | 
| + | 
| +        //  Make element's interceptor a CustomElementClass. | 
| +        _blink.Blink_Utils.setInstanceInterceptorCustomUpgrade($this); | 
| + | 
| if (oldCreatedCallback != null) | 
| oldCreatedCallback.apply([], thisArg: $this); | 
| })); | 
|  |