Invalidate :default pseudo classes when a default button is added or removed.

third_party/WebKit/Source/core/html/HTMLInputElement.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, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2007 Samuel Weinig (sam@webkit.org)
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2012 Samsung Electronics. All rights reserved.
@@ skipping 457 matching lines @@
 
     const AtomicString& newTypeName = InputType::normalizeTypeName(fastGetAttribute(typeAttr));
     if (m_inputType->formControlType() == newTypeName)
         return;
 
     RefPtrWillBeRawPtr<InputType> newType = InputType::create(*this, newTypeName);
     removeFromRadioButtonGroup();
 
     bool didStoreValue = m_inputType->storesValueSeparateFromAttribute();
     bool didRespectHeightAndWidth = m_inputType->shouldRespectHeightAndWidthAttributes();
+    bool couldBeSuccessfulSubmitButton = canBeSuccessfulSubmitButton();
 
     m_inputTypeView->destroyShadowSubtree();
     lazyReattachIfAttached();
 
     m_inputType = newType.release();
     if (openShadowRoot())
         m_inputTypeView = InputTypeView::create(*this);
     else
         m_inputTypeView = m_inputType;
     m_inputTypeView->createShadowSubtree();
@@ skipping 34 matching lines @@
 
     if (document().focusedElement() == this)
         document().updateFocusAppearanceSoon(SelectionBehaviorOnFocus::Restore);
 
     setTextAsOfLastFormControlChangeEvent(value());
     setChangedSinceLastFormControlChangeEvent(false);
 
     addToRadioButtonGroup();
 
     setNeedsValidityCheck();
+    if ((couldBeSuccessfulSubmitButton || canBeSuccessfulSubmitButton()) && formOwner() && inDocument())
+        formOwner()->invalidateDefaultButtonStyle();
     notifyFormStateChanged();
 }
 
 void HTMLInputElement::subtreeHasChanged()
 {
     m_inputTypeView->subtreeHasChanged();
     // When typing in an input field, childrenChanged is not called, so we need to force the directionality check.
     calculateAndAdjustDirectionality();
 }
 
@@ skipping 1386 matching lines @@
 void HTMLInputElement::ensurePrimaryContent()
 {
     m_inputTypeView->ensurePrimaryContent();
 }
 
 bool HTMLInputElement::hasFallbackContent() const
 {
     return m_inputTypeView->hasFallbackContent();
 }
 } // namespace blink