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

third_party/WebKit/Source/core/dom/Node.cpp

Index: third_party/WebKit/Source/core/dom/Node.cpp
diff --git a/third_party/WebKit/Source/core/dom/Node.cpp b/third_party/WebKit/Source/core/dom/Node.cpp
index a834c8b5463ed24fa606b1d574f35798798572cf..237ae2a7914b61dcbfe6a2fdc4f899929e799bad 100644
--- a/third_party/WebKit/Source/core/dom/Node.cpp
+++ b/third_party/WebKit/Source/core/dom/Node.cpp
@@ -970,6 +970,7 @@ bool Node::isStyledElement() const
 
 bool Node::canParticipateInFlatTree() const
 {
+    // TODO(hayato): Return false for pseudo elements.
     return !isShadowRoot() && !isSlotOrActiveInsertionPoint();
 }
 
@@ -2184,6 +2185,7 @@ StaticNodeList* Node::getDestinationInsertionPoints()
 
 HTMLSlotElement* Node::assignedSlot() const
 {
+    DCHECK(!isPseudoElement());
     if (ShadowRoot* root = v1ShadowRootOfParent())
         return root->ensureSlotAssignment().findSlot(*this);
     return nullptr;