Fix a crash when pseudo elements are used for a shadow host

third_party/WebKit/Source/core/dom/Node.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.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 952 matching lines @@
 // PseudoElements and VTTElements. It's possible we can just eliminate all the checks
 // since those elements will never have class names, inline style, or other things that
 // this apparently guards against.
 bool Node::isStyledElement() const
 {
     return isHTMLElement() || isSVGElement() || (isElementNode() && toElement(this)->namespaceURI() == MathMLNames::mathmlNamespaceURI);
 }
 
 bool Node::canParticipateInFlatTree() const
 {
+    // TODO(hayato): Return false for pseudo elements.
     return !isShadowRoot() && !isSlotOrActiveInsertionPoint();
 }
 
 bool Node::isSlotOrActiveInsertionPoint() const
 {
     return isHTMLSlotElement(*this) || isActiveInsertionPoint(*this);
 }
 
 AtomicString Node::slotName() const
 {
@@ skipping 1194 matching lines @@
         DCHECK(insertionPoint->containingShadowRoot());
         if (!insertionPoint->containingShadowRoot()->isOpenOrV0())
             break;
         filteredInsertionPoints.append(insertionPoint);
     }
     return StaticNodeList::adopt(filteredInsertionPoints);
 }
 
 HTMLSlotElement* Node::assignedSlot() const
 {
+    DCHECK(!isPseudoElement());
     if (ShadowRoot* root = v1ShadowRootOfParent())
         return root->ensureSlotAssignment().findSlot(*this);
     return nullptr;
 }
 
 HTMLSlotElement* Node::assignedSlotForBinding()
 {
     updateDistribution();
     if (ShadowRoot* root = v1ShadowRootOfParent()) {
         if (root->type() == ShadowRootType::Open)
@@ skipping 232 matching lines @@
 
 void showNodePath(const blink::Node* node)
 {
     if (node)
         node->showNodePathForThis();
     else
         fprintf(stderr, "Cannot showNodePath for (nil)\n");
 }
 
 #endif