[New Multicolumn] Actual support for layout of column-span:all.

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 307 matching lines @@
         return !isTable();
     else if (newChild->isTableSection())
         return !isTable();
     else if (newChild->isTableRow())
         return !isTableSection();
     else if (newChild->isTableCell())
         return !isTableRow();
     return false;
 }
 
+bool RenderObject::isValidColumnSpanAll() const
+{
+    ASSERT(style()->columnSpan() == ColumnSpanAll);
+    RenderFlowThread* flowThread = flowThreadContainingBlock();
+    return flowThread && flowThread->isColumnSpanner(this);
+}
+
 void RenderObject::addChild(RenderObject* newChild, RenderObject* beforeChild)
 {
     ASSERT(isAllowedToModifyRenderTreeStructure(document()));
 
     RenderObjectChildList* children = virtualChildren();
     ASSERT(children);
     if (!children)
         return;
 
     if (requiresAnonymousTableWrappers(newChild)) {
@@ skipping 2849 matching lines @@
 {
     if (object1) {
         const blink::RenderObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showRenderTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif