[New Multicolumn] Add RenderMultiColumnSpannerSet.

Source/core/rendering/RenderObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 2352 matching lines @@
     // that needs to be drawn and layer visibility optimization can't be used
     if (parent()->style()->visibility() != VISIBLE && style()->visibility() == VISIBLE && !hasLayer()) {
         if (!layer)
             layer = parent()->enclosingLayer();
         if (layer)
             layer->dirtyVisibleContentStatus();
     }
 
     if (!isFloating() && parent()->childrenInline())
         parent()->dirtyLinesFromChangedChild(this);
+
+    if (RenderFlowThread* flowThread = parent()->flowThreadContainingBlock())
+        flowThread->flowThreadDescendantWasInserted(this);
 }
 
 void RenderObject::willBeRemovedFromTree()
 {
     // FIXME: We should ASSERT(isRooted()) but we have some out-of-order removals which would need to be fixed first.
 
     // If we remove a visible child from an invisible parent, we don't know the layer visibility any more.
     RenderLayer* layer = 0;
     if (parent()->style()->visibility() != VISIBLE && style()->visibility() == VISIBLE && !hasLayer()) {
         layer = parent()->enclosingLayer();
@@ skipping 29 matching lines @@
     // Pass in the flow thread so that we don't have to look it up for all the children.
     removeFromRenderFlowThreadRecursive(flowThreadContainingBlock());
 }
 
 void RenderObject::removeFromRenderFlowThreadRecursive(RenderFlowThread* renderFlowThread)
 {
     if (const RenderObjectChildList* children = virtualChildren()) {
         for (RenderObject* child = children->firstChild(); child; child = child->nextSibling())
             child->removeFromRenderFlowThreadRecursive(renderFlowThread);
     }
-
     setFlowThreadState(NotInsideFlowThread);
 }
 
 void RenderObject::destroyAndCleanupAnonymousWrappers()
 {
     // If the tree is destroyed, there is no need for a clean-up phase.
     if (documentBeingDestroyed()) {
         destroy();
         return;
     }
@@ skipping 701 matching lines @@
 {
     if (object1) {
         const blink::RenderObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showRenderTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif