Changing out-of-flow-ness on a multicol child may affect the need for column sets.

Source/core/layout/LayoutObject.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 1736 matching lines @@
         ASSERT(!isLayoutIFrame() && !isEmbeddedObject() && !isCanvas());
         return;
     }
 
     StyleDifference diff;
     if (m_style)
         diff = m_style->visualInvalidationDiff(*style);
 
     diff = adjustStyleDifference(diff);
 
+    if (m_style) {
+        if (LayoutFlowThread* flowThread = flowThreadContainingBlock())
+            flowThread->flowThreadDescendantStyleWillChange(this, diff, *style);
+    }
     styleWillChange(diff, *style);
 
     RefPtr<ComputedStyle> oldStyle = m_style.release();
     setStyleInternal(style);
 
     updateFillImages(oldStyle ? &oldStyle->backgroundLayers() : 0, m_style->backgroundLayers());
     updateFillImages(oldStyle ? &oldStyle->maskLayers() : 0, m_style->maskLayers());
 
     updateImage(oldStyle ? oldStyle->borderImage().image() : 0, m_style->borderImage().image());
     updateImage(oldStyle ? oldStyle->maskBoxImage().image() : 0, m_style->maskBoxImage().image());
 
     updateShapeImage(oldStyle ? oldStyle->shapeOutside() : 0, m_style->shapeOutside());
 
     bool doesNotNeedLayoutOrPaintInvalidation = !m_parent;
 
     styleDidChange(diff, oldStyle.get());
+    if (oldStyle.get()) {
+        if (LayoutFlowThread* flowThread = flowThreadContainingBlock())
+            flowThread->flowThreadDescendantStyleDidChange(this, diff, *oldStyle.get());
+    }
 
     // FIXME: |this| might be destroyed here. This can currently happen for a LayoutTextFragment when
     // its first-letter block gets an update in LayoutTextFragment::styleDidChange. For LayoutTextFragment(s),
     // we will safely bail out with the doesNotNeedLayoutOrPaintInvalidation flag. We might want to broaden
     // this condition in the future as we move layoutObject changes out of layout and into style changes.
     if (doesNotNeedLayoutOrPaintInvalidation)
         return;
 
     // Now that the layer (if any) has been updated, we need to adjust the diff again,
     // check whether we should layout now, and decide if we need to invalidate paints.
@@ skipping 1512 matching lines @@
         const blink::LayoutObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showLayoutTreeAndMark(object1, "*", object2, "-", 0);
     } else {
         fprintf(stderr, "Cannot showLayoutTree. Root is (nil)\n");
     }
 }
 
 #endif