Need to roll back the multicol machinery state when re-laying out a block child.

third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp

 /*
  * Copyright (C) 2012 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1029 matching lines @@
             return false;
         }
         if (canContainSpannerInParentFragmentationContext(*object))
             next = object->nextInPreOrder(&root);
         else
             next = object->nextInPreOrderAfterChildren(&root);
     }
     return true;
 }
 
+MultiColumnLayoutState LayoutMultiColumnFlowThread::multiColumnLayoutState() const
+{
+    return MultiColumnLayoutState(m_lastSetWorkedOn);
+}
+
+void LayoutMultiColumnFlowThread::restoreMultiColumnLayoutState(const MultiColumnLayoutState& state)
+{
+    m_lastSetWorkedOn = state.columnSet();
+}
+
 } // namespace blink