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

third_party/WebKit/Source/core/css/RuleFeature.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 308 matching lines @@
         case CSSSelector::PseudoLink:
         case CSSSelector::PseudoVisited:
         case CSSSelector::PseudoAnyLink:
         case CSSSelector::PseudoAutofill:
         case CSSSelector::PseudoHover:
         case CSSSelector::PseudoDrag:
         case CSSSelector::PseudoFocus:
         case CSSSelector::PseudoActive:
         case CSSSelector::PseudoChecked:
         case CSSSelector::PseudoEnabled:
-        // TODO(rune@opera.com): crbug.com/557683 :default is currently not updated dynamically.
-        // case CSSSelector::Default:
+        case CSSSelector::PseudoDefault:
         case CSSSelector::PseudoDisabled:
         case CSSSelector::PseudoOptional:
         case CSSSelector::PseudoPlaceholderShown:
         case CSSSelector::PseudoRequired:
         case CSSSelector::PseudoReadOnly:
         case CSSSelector::PseudoReadWrite:
         case CSSSelector::PseudoValid:
         case CSSSelector::PseudoInvalid:
         case CSSSelector::PseudoIndeterminate:
         case CSSSelector::PseudoTarget:
@@ skipping 437 matching lines @@
 
 DEFINE_TRACE(RuleFeatureSet)
 {
 #if ENABLE(OILPAN)
     visitor->trace(siblingRules);
     visitor->trace(uncommonAttributeRules);
 #endif
 }
 
 } // namespace blink