[selectors4] Implement :focus-within pseudo-class

third_party/WebKit/Source/core/css/CSSSelector.h

 /*
  * Copyright (C) 1999-2003 Lars Knoll (knoll@kde.org)
  *               1999 Waldo Bastian (bastian@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2008, 2009, 2010, 2013 Apple Inc. All rights
  * reserved.
  *
  * 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 141 matching lines @@
     kPseudoNthLastChild,
     kPseudoNthLastOfType,
     kPseudoLink,
     kPseudoVisited,
     kPseudoAny,
     kPseudoAnyLink,
     kPseudoAutofill,
     kPseudoHover,
     kPseudoDrag,
     kPseudoFocus,
+    kPseudoFocusWithin,
     kPseudoActive,
     kPseudoChecked,
     kPseudoEnabled,
     kPseudoFullPageMedia,
     kPseudoDefault,
     kPseudoDisabled,
     kPseudoOptional,
     kPseudoPlaceholderShown,
     kPseudoRequired,
     kPseudoReadOnly,
@@ skipping 352 matching lines @@
   DCHECK_NE(match_, static_cast<unsigned>(kTag));
   if (has_rare_data_)
     return data_.rare_data_->serializing_value_;
   // AtomicString is really just a StringImpl* so the cast below is safe.
   // FIXME: Perhaps call sites could be changed to accept StringImpl?
   return *reinterpret_cast<const AtomicString*>(&data_.value_);
 }
 
 inline bool CSSSelector::IsUserActionPseudoClass() const {
   return pseudo_type_ == kPseudoHover || pseudo_type_ == kPseudoActive ||
-         pseudo_type_ == kPseudoFocus || pseudo_type_ == kPseudoDrag;
+         pseudo_type_ == kPseudoFocus || pseudo_type_ == kPseudoDrag ||
+         pseudo_type_ == kPseudoFocusWithin;
 }
 
 inline bool CSSSelector::IsIdClassOrAttributeSelector() const {
   return IsAttributeSelector() || Match() == CSSSelector::kId ||
          Match() == CSSSelector::kClass;
 }
 
 }  // namespace blink
 
 #endif  // CSSSelector_h