Disable layout optimization when column height may be non-uniform.

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

 /*
  * 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 198 matching lines @@
 
   LayoutUnit tallestUnbreakableLogicalHeight(
       LayoutUnit offsetInFlowThread) const;
 
   LayoutSize columnOffset(const LayoutPoint&) const final;
 
   // Do we need to set a new width and lay out?
   virtual bool needsNewWidth() const;
 
   bool isPageLogicalHeightKnown() const final;
+  bool mayHaveNonUniformPageLogicalHeight() const final;
 
   LayoutSize flowThreadTranslationAtOffset(LayoutUnit,
                                            PageBoundaryRule,
                                            CoordinateSpaceConversion) const;
   LayoutSize flowThreadTranslationAtPoint(const LayoutPoint& flowThreadPoint,
                                           CoordinateSpaceConversion) const;
 
   LayoutPoint flowThreadPointToVisualPoint(
       const LayoutPoint& flowThreadPoint) const override;
   LayoutPoint visualPointToFlowThreadPoint(
@@ skipping 139 matching lines @@
 // LayoutObject.
 DEFINE_TYPE_CASTS(LayoutMultiColumnFlowThread,
                   LayoutFlowThread,
                   object,
                   object->isLayoutMultiColumnFlowThread(),
                   object.isLayoutMultiColumnFlowThread());
 
 }  // namespace blink
 
 #endif  // LayoutMultiColumnFlowThread_h