Reattach whitespace siblings only when needed

Source/core/dom/RenderTreeBuilder.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, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2011 Google 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
@@ skipping 102 matching lines @@
             return m_node->document().renderView();
     }
 
     return RenderTreeBuilder::parentRenderer();
 }
 
 void RenderTreeBuilderForElement::createRenderer()
 {
     ASSERT(rendererIsNeeded());
     ASSERT(!m_node->renderer());
+    ASSERT(m_node->needsAttach());
 
     Element* element = toElement(m_node);
     RenderStyle& style = *m_style.get();
 
     RenderObject* newRenderer = element->createRenderer(&style);
     if (!newRenderer)
         return;
 
     RenderObject* parentRenderer = this->parentRenderer();
 
@@ skipping 25 matching lines @@
     if (!RenderTreeBuilder::rendererIsNeeded())
         return false;
 
     return toText(m_node)->textRendererIsNeeded(*parentRenderer()->style(), *parentRenderer());
 }
 
 void RenderTreeBuilderForText::createRenderer()
 {
     ASSERT(rendererIsNeeded());
     ASSERT(!m_node->renderer());
+    ASSERT(m_node->needsAttach());
 
     Text* textNode = toText(m_node);
     RenderObject* parentRenderer = this->parentRenderer();
     RenderStyle* style = parentRenderer->style();
 
     RenderText* newRenderer = textNode->createTextRenderer(style);
     if (!parentRenderer->isChildAllowed(newRenderer, style)) {
         newRenderer->destroy();
         return;
     }
 
     // Make sure the RenderObject already knows it is going to be added to a RenderFlowThread before we set the style
     // for the first time. Otherwise code using inRenderFlowThread() in the styleWillChange and styleDidChange will fail.
     newRenderer->setFlowThreadState(parentRenderer->flowThreadState());
 
     RenderObject* nextRenderer = this->nextRenderer();
     textNode->setRenderer(newRenderer);
     // Parent takes care of the animations, no need to call setAnimatableStyle.
     newRenderer->setStyle(style);
     parentRenderer->addChild(newRenderer, nextRenderer);
 }
 
 }