Don't persist plugins across reattach for widget updates.

third_party/WebKit/Source/core/html/HTMLPlugInElement.cpp

 /**
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Stefan Schimanski (1Stein@gmx.de)
  * Copyright (C) 2004, 2005, 2006 Apple Computer, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 615 matching lines @@
     return false;
 }
 
 bool HTMLPlugInElement::useFallbackContent() const
 {
     return openShadowRoot();
 }
 
 void HTMLPlugInElement::lazyReattachIfNeeded()
 {
-    if (!useFallbackContent() && needsWidgetUpdate() && layoutObject() && !isImageType())
+    if (!useFallbackContent() && needsWidgetUpdate() && layoutObject() && !isImageType()) {
         lazyReattachIfAttached();
+        setPersistedPluginWidget(nullptr);
+    }
 }
 
 } // namespace blink