Add infrastructure for partial layouts

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 715 matching lines @@
 }
 
 #ifndef NDEBUG
 void RenderObject::checkBlockPositionedObjectsNeedLayout()
 {
     ASSERT(!needsLayout());
 
     if (isRenderBlock())
         toRenderBlock(this)->checkPositionedObjectsNeedLayout();
 }
+
+void RenderObject::checkNotInPartialLayout()
+{
+    // During partial layout, setNeedsLayout(true or false) should not be called.
+    ASSERT(!frameView()->partialLayout().isStopping());
+}
 #endif
 
 void RenderObject::setPreferredLogicalWidthsDirty(MarkingBehavior markParents)
 {
     bool alreadyDirty = preferredLogicalWidthsDirty();
     m_bitfields.setPreferredLogicalWidthsDirty(true);
     if (!alreadyDirty && markParents == MarkContainingBlockChain && (isText() || !style()->hasOutOfFlowPosition()))
         invalidateContainerPreferredLogicalWidths();
 }
 
@@ skipping 2564 matching lines @@
 {
     if (object1) {
         const WebCore::RenderObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showRenderTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif