Add support for printing multicol containers, and enable it.

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

 // 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.
 
 #ifndef MultiColumnFragmentainerGroup_h
 #define MultiColumnFragmentainerGroup_h
 
 #include "core/layout/LayoutMultiColumnFlowThread.h"
 #include "wtf/Allocator.h"
 
@@ skipping 26 matching lines @@
     bool isLastGroup() const;
 
     // Position within the LayoutMultiColumnSet.
     LayoutUnit logicalTop() const { return m_logicalTop; }
     void setLogicalTop(LayoutUnit logicalTop) { m_logicalTop = logicalTop; }
 
     LayoutUnit logicalHeight() const { return m_columnHeight; }
 
     LayoutSize offsetFromColumnSet() const;
 
-    // Return the block offset from the enclosing flow thread, if nested. In the coordinate space
-    // of the enclosing flow thread.
-    LayoutUnit blockOffsetInEnclosingFlowThread() const;
+    // Return the block offset from the enclosing fragmentation context, if nested. In the
+    // coordinate space of the enclosing fragmentation context.
+    LayoutUnit blockOffsetInEnclosingFragmentationContext() const;
 
     // The top of our flow thread portion
     LayoutUnit logicalTopInFlowThread() const { return m_logicalTopInFlowThread; }
     void setLogicalTopInFlowThread(LayoutUnit logicalTopInFlowThread) { m_logicalTopInFlowThread = logicalTopInFlowThread; }
 
     // The bottom of our flow thread portion
     LayoutUnit logicalBottomInFlowThread() const { return m_logicalBottomInFlowThread; }
     void setLogicalBottomInFlowThread(LayoutUnit logicalBottomInFlowThread) { ASSERT(logicalBottomInFlowThread >= m_logicalTopInFlowThread); m_logicalBottomInFlowThread = logicalBottomInFlowThread; }
 
     // The height of our flow thread portion
@@ skipping 91 matching lines @@
 
 private:
     LayoutMultiColumnSet& m_columnSet;
 
     Vector<MultiColumnFragmentainerGroup, 1> m_groups;
 };
 
 } // namespace blink
 
 #endif // MultiColumnFragmentainerGroup_h