Multi-column properties in a flexbox hide its content

Source/core/rendering/RenderBlock.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. 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
  * License as published by the Free Software Foundation; either
@@ skipping 3286 matching lines @@
 
 bool RenderBlock::requiresColumns(int desiredColumnCount) const
 {
     // Paged overflow is treated as multicol here, unless this element was the one that got its
     // overflow propagated to the viewport.
     bool isPaginated = style()->isOverflowPaged() && node() != document().viewportDefiningElement();
 
     return firstChild()
         && (desiredColumnCount != 1 || !style()->hasAutoColumnWidth() || isPaginated)
         && !firstChild()->isAnonymousColumnsBlock()
-        && !firstChild()->isAnonymousColumnSpanBlock();
+        && !firstChild()->isAnonymousColumnSpanBlock() && !isFlexibleBoxIncludingDeprecated();
 }
 
 void RenderBlock::setDesiredColumnCountAndWidth(int count, LayoutUnit width)
 {
     bool destroyColumns = !requiresColumns(count);
     if (destroyColumns) {
         if (hasColumns()) {
             gColumnInfoMap->take(this);
             setHasColumns(false);
         }
@@ skipping 1534 matching lines @@
 void RenderBlock::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const RenderObject* obj) const
 {
     showRenderObject();
     for (const RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox())
         root->showLineTreeAndMark(markedBox1, markedLabel1, markedBox2, markedLabel2, obj, 1);
 }
 
 #endif
 
 } // namespace blink