Add support for printing multicol containers, and enable it.

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

Index: third_party/WebKit/Source/core/layout/ColumnBalancer.cpp
diff --git a/third_party/WebKit/Source/core/layout/ColumnBalancer.cpp b/third_party/WebKit/Source/core/layout/ColumnBalancer.cpp
index 29bfd96d52e8bbb3b0d87acbd790892468def1af..60678cb328c4885b29e749b144a14213b7514e1f 100644
--- a/third_party/WebKit/Source/core/layout/ColumnBalancer.cpp
+++ b/third_party/WebKit/Source/core/layout/ColumnBalancer.cpp
@@ -116,7 +116,7 @@ void InitialColumnHeightFinder::examineBoxAfterEntering(const LayoutBox& box)
         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);
         }