Add support for printing multicol containers, and enable it.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "core/layout/ColumnBalancer.h"
 
 #include "core/layout/LayoutMultiColumnFlowThread.h"
 #include "core/layout/LayoutMultiColumnSet.h"
@@ skipping 98 matching lines @@
     if (box.hasForcedBreakAfter())
         addContentRun(flowThreadOffset() + box.logicalHeight());
 
     if (box.paginationBreakability() != LayoutBox::AllowAnyBreaks) {
         LayoutUnit unsplittableLogicalHeight = box.logicalHeight();
         if (box.isFloating())
             unsplittableLogicalHeight += box.marginBefore() + box.marginAfter();
         m_tallestUnbreakableLogicalHeight = std::max(m_tallestUnbreakableLogicalHeight, unsplittableLogicalHeight);
     } else if (box.isLayoutBlockFlow()) {
         if (LayoutMultiColumnFlowThread* innerFlowThread = toLayoutBlockFlow(box).multiColumnFlowThread()) {
-            LayoutUnit offsetInInnerFlowThread = flowThreadOffset() - innerFlowThread->blockOffsetInEnclosingFlowThread();
+            LayoutUnit offsetInInnerFlowThread = flowThreadOffset() - innerFlowThread->blockOffsetInEnclosingFragmentationContext();
             LayoutUnit innerUnbreakableHeight = innerFlowThread->tallestUnbreakableLogicalHeight(offsetInInnerFlowThread);
             m_tallestUnbreakableLogicalHeight = std::max(m_tallestUnbreakableLogicalHeight, innerUnbreakableHeight);
         }
     }
 }
 
 void InitialColumnHeightFinder::examineBoxBeforeLeaving(const LayoutBox& box)
 {
 }
 
@@ skipping 183 matching lines @@
         recordSpaceShortage(logicalOffsetFromCurrentColumn + lineHeight - m_pendingStrut);
         m_pendingStrut = LayoutUnit::min();
         return;
     }
     ASSERT(isFirstAfterBreak(lineTopInFlowThread) || !line.paginationStrut());
     if (isFirstAfterBreak(lineTopInFlowThread))
         recordSpaceShortage(lineHeight - line.paginationStrut());
 }
 
 } // namespace blink