Style invalidation support for :first/last/only-child.

third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 184 matching lines @@
     }
 
     DocumentFragment::removedFrom(insertionPoint);
 }
 
 void ShadowRoot::childrenChanged(const ChildrenChange& change)
 {
     ContainerNode::childrenChanged(change);
 
     if (change.isChildElementChange())
-        checkForSiblingStyleChanges(change.type == ElementRemoved ? SiblingElementRemoved : SiblingElementInserted, change.siblingChanged, change.siblingBeforeChange, change.siblingAfterChange);
+        checkForSiblingStyleChanges(change.type == ElementRemoved ? SiblingElementRemoved : SiblingElementInserted, toElement(change.siblingChanged), change.siblingBeforeChange, change.siblingAfterChange);
 
     if (InsertionPoint* point = shadowInsertionPointOfYoungerShadowRoot()) {
         if (ShadowRoot* root = point->containingShadowRoot())
             root->owner()->setNeedsDistributionRecalc();
     }
 }
 
 void ShadowRoot::registerScopedHTMLStyleChild()
 {
     ++m_numberOfStyles;
@@ skipping 119 matching lines @@
         ostream << "ShadowRootType::Open";
         break;
     case ShadowRootType::Closed:
         ostream << "ShadowRootType::Closed";
         break;
     }
     return ostream;
 }
 
 } // namespace blink