Implement /content/ combinator.

Source/core/css/SelectorChecker.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, 2013 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 120 matching lines @@
 {
     // first selector has to match
     unsigned specificity = 0;
     if (!checkOne(context, siblingTraversalStrategy, &specificity))
         return SelectorFailsLocally;
 
     if (context.selector->m_match == CSSSelector::PseudoElement) {
         if (context.selector->isCustomPseudoElement()) {
             if (!matchesCustomPseudoElement(context.element, *context.selector))
                 return SelectorFailsLocally;
-        } else if (context.selector->isContentPseudoElement()) {
-            if (!context.element->isInShadowTree() || !context.element->isInsertionPoint())
-                return SelectorFailsLocally;
         } else {
             if ((!context.elementStyle && m_mode == ResolvingStyle) || m_mode == QueryingRules)
                 return SelectorFailsLocally;
 
             PseudoId pseudoId = CSSSelector::pseudoId(context.selector->pseudoType());
             if (pseudoId == FIRST_LETTER)
                 context.element->document().styleEngine()->setUsesFirstLetterRules(true);
             if (pseudoId != NOPSEUDO && m_mode != SharingRules && result)
                 result->dynamicPseudo = pseudoId;
         }
@@ skipping 102 matching lines @@
                 return matchForShadowDistributed(context.element, siblingTraversalStrategy, nextContext, result);
 
             nextContext.element = parentElement(context);
             if (!nextContext.element)
                 return SelectorFailsCompletely;
 
             nextContext.isSubSelector = false;
             nextContext.elementStyle = 0;
             return match(nextContext, siblingTraversalStrategy, result);
         }
+
+    case CSSSelector::ShadowContent:
+        return matchForShadowDistributed(context.element, siblingTraversalStrategy, nextContext, result);
+
     case CSSSelector::DirectAdjacent:
         if (m_mode == ResolvingStyle) {
             if (Node* parent = context.element->parentElementOrShadowRoot())
                 SiblingRuleHelper(parent).setChildrenAffectedByDirectAdjacentRules();
         }
         nextContext.element = ElementTraversal::previousSibling(*context.element);
         if (!nextContext.element)
             return SelectorFailsAllSiblings;
         nextContext.isSubSelector = false;
         nextContext.elementStyle = 0;
@@ skipping 807 matching lines @@
     return element.focused() && isFrameFocused(element);
 }
 
 template
 SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext&, const DOMSiblingTraversalStrategy&, MatchResult*) const;
 
 template
 SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext&, const ShadowDOMSiblingTraversalStrategy&, MatchResult*) const;
 
 }