Make sure Document::updateLayoutTree*() is called before Element::isFocusable().

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2010 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
  * 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
@@ skipping 37 matching lines @@
     if (!fieldset)
         return nullptr;
 
     // Find first form element inside the fieldset that is not a legend element.
     // FIXME: Should we consider tabindex?
     return Traversal<HTMLFormControlElement>::next(*fieldset, fieldset);
 }
 
 void HTMLLegendElement::focus(const FocusParams& params)
 {
+    document().updateLayoutTreeIgnorePendingStylesheets();
     if (isFocusable()) {
         Element::focus(params);
         return;
     }
 
     // To match other browsers' behavior, never restore previous selection.
     if (HTMLFormControlElement* control = associatedControl())
         control->focus(FocusParams(SelectionBehaviorOnFocus::Reset, params.type, params.sourceCapabilities));
 }
 
 void HTMLLegendElement::accessKeyAction(bool sendMouseEvents)
 {
     if (HTMLFormControlElement* control = associatedControl())
         control->accessKeyAction(sendMouseEvents);
 }
 
 HTMLFormElement* HTMLLegendElement::form() const
 {
     // According to the specification, If the legend has a fieldset element as
     // its parent, then the form attribute must return the same value as the
     // form attribute on that fieldset element. Otherwise, it must return null.
     ContainerNode* fieldset = parentNode();
     if (!isHTMLFieldSetElement(fieldset))
         return nullptr;
 
     return toHTMLFieldSetElement(fieldset)->formOwner();
 }
 
 } // namespace blink