Remove unnecessary RenderFlowThread usage and inclusion.

Source/core/rendering/RenderBlock.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. 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
@@ skipping 1975 matching lines @@
 TrackedRendererListHashSet* RenderBlock::positionedObjects() const
 {
     if (gPositionedDescendantsMap)
         return gPositionedDescendantsMap->get(this);
     return 0;
 }
 
 void RenderBlock::insertPositionedObject(RenderBox* o)
 {
     ASSERT(!isAnonymousBlock());
-
-    if (o->isRenderFlowThread())
-        return;
-
     insertIntoTrackedRendererMaps(o, gPositionedDescendantsMap, gPositionedContainerMap);
 }
 
 void RenderBlock::removePositionedObject(RenderBox* o)
 {
     removeFromTrackedRendererMaps(o, gPositionedDescendantsMap, gPositionedContainerMap);
 }
 
 void RenderBlock::removePositionedObjects(RenderBlock* o, ContainingBlockState containingBlockState)
 {
@@ skipping 1911 matching lines @@
 void RenderBlock::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const RenderObject* obj) const
 {
     showRenderObject();
     for (const RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox())
         root->showLineTreeAndMark(markedBox1, markedLabel1, markedBox2, markedLabel2, obj, 1);
 }
 
 #endif
 
 } // namespace blink