removeBetween() -> detach() performance fix.

third_party/WebKit/Source/core/dom/ContainerNode.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, 2013 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 588 matching lines @@
 }
 
 void ContainerNode::removeBetween(Node* previousChild, Node* nextChild, Node& oldChild)
 {
     EventDispatchForbiddenScope assertNoEventDispatch;
 
     ASSERT(oldChild.parentNode() == this);
 
     AttachContext context;
     context.clearInvalidation = true;
-    if (!needsAttach() || !oldChild.needsAttach())
+    if (!oldChild.needsAttach())
         oldChild.detach(context);
+    else if (oldChild.needsStyleInvalidation())
+        document().styleEngine().styleInvalidator().clearInvalidation(toElement(oldChild));

[esprehn, 2016/01/15 00:31:45]

can Element::removedFrom do this? It seems like it belongs there with the other
Element clean up code.

[rune, 2016/01/15 09:42:41]

Yeah, I think so. It means it'll check needsStyleInvalidation() both in detach()
and removedFrom(), for the non-root elements, in the case where we're removing
the element from the document, but that's probably ok (clearInvalidation() only
called once, of course).

[rune, 2016/01/15 13:25:41]

Done.

 
     if (nextChild)
         nextChild->setPreviousSibling(previousChild);
     if (previousChild)
         previousChild->setNextSibling(nextChild);
     if (m_firstChild == &oldChild)
         m_firstChild = nextChild;
     if (m_lastChild == &oldChild)
         m_lastChild = previousChild;
 
@@ skipping 922 matching lines @@
         return true;
 
     if (node->isElementNode() && toElement(node)->shadow())
         return true;
 
     return false;
 }
 #endif
 
 } // namespace blink