[css-display] Support pseudo-elements on display: contents elements.

third_party/WebKit/Source/core/css/resolver/StyleResolver.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/)
@@ skipping 808 matching lines @@
 
 PseudoElement* StyleResolver::createPseudoElement(Element* parent,
                                                   PseudoId pseudoId) {
   if (pseudoId == PseudoIdFirstLetter)
     return FirstLetterPseudoElement::create(parent);
   return PseudoElement::create(parent, pseudoId);
 }
 
 PseudoElement* StyleResolver::createPseudoElementIfNeeded(Element& parent,
                                                           PseudoId pseudoId) {
+  if (!parent.canGeneratePseudoElement(pseudoId))
+    return nullptr;
+
   LayoutObject* parentLayoutObject = parent.layoutObject();
+  if (!parentLayoutObject) {
+    DCHECK(parent.hasDisplayContentsStyle());
+    parentLayoutObject = LayoutTreeBuilderTraversal::parentLayoutObject(parent);
+  }
+
   if (!parentLayoutObject)
     return nullptr;
 
+  ComputedStyle* parentStyle = parent.mutableComputedStyle();
+  DCHECK(parentStyle);
+
   // The first letter pseudo element has to look up the tree and see if any
   // of the ancestors are first letter.
   if (pseudoId < FirstInternalPseudoId && pseudoId != PseudoIdFirstLetter &&
-      !parentLayoutObject->style()->hasPseudoStyle(pseudoId))
+      !parentStyle->hasPseudoStyle(pseudoId)) {
     return nullptr;
+  }
 
   if (pseudoId == PseudoIdBackdrop && !parent.isInTopLayer())
     return nullptr;
 
   if (pseudoId == PseudoIdFirstLetter &&
       (parent.isSVGElement() ||
        !FirstLetterPseudoElement::firstLetterTextLayoutObject(parent)))
     return nullptr;
 
   if (!canHaveGeneratedChildren(*parentLayoutObject))
     return nullptr;
 
-  ComputedStyle* parentStyle = parentLayoutObject->mutableStyle();
   if (ComputedStyle* cachedStyle =
           parentStyle->getCachedPseudoStyle(pseudoId)) {
     if (!pseudoElementLayoutObjectIsNeeded(cachedStyle))
       return nullptr;
     return createPseudoElement(&parent, pseudoId);
   }
 
-  StyleResolverState state(document(), &parent, parentStyle, parentStyle);
+  StyleResolverState state(document(), &parent, parentStyle,
+                           parentLayoutObject->style());
   if (!pseudoStyleForElementInternal(parent, pseudoId, parentStyle, state))
     return nullptr;
   RefPtr<ComputedStyle> style = state.takeStyle();
   DCHECK(style);
   parentStyle->addCachedPseudoStyle(style);
 
   if (!pseudoElementLayoutObjectIsNeeded(style.get()))
     return nullptr;
 
   PseudoElement* pseudo = createPseudoElement(&parent, pseudoId);
@@ skipping 1101 matching lines @@
 
 DEFINE_TRACE(StyleResolver) {
   visitor->trace(m_matchedPropertiesCache);
   visitor->trace(m_selectorFilter);
   visitor->trace(m_styleSharingLists);
   visitor->trace(m_document);
   visitor->trace(m_tracker);
 }
 
 }  // namespace blink